NES NBE Series Manual

NBE O & M Document No. NES/NBE/O&M Page 1
of 43
N
E
S
C
O
M
P
A
N
Y
EXPERT IN ENGINEERED
VACUUM SYSTEMS SINCE 1993
Performance. Reliability. Efficiency.
333 Rt 46 W
Building A,
Fairfield, NJ 07004
1-800-297-3550
www.nescompany.com
Operation &
Maintenance Manual
for NBE Series
Vacuum Pumps &
Compressors
WARNING
Do not operate PUMP before primed and connected to the constant supply of clean compressant Liquid. IF RUN
DRY, PUMP WILL BE DAMAGED; always use a strainer to prevent sand and scale from entering the pump with
liquid sealant.
Specific operating conditions combined with water hardness may result in excessive lime deposits inside the pump,
causing it to bind. Should this condition be evident, flush the pump with a solvent at regular intervals.
This pump has been drained and flushed with water-soluble preservative oil before shipment. After the pump has
been in service, do not store without draining as specified in this manual. The freezing of the preservative oil can
damage the pump.
USE CAUTION when removing inlet screens. Any foreign material on the screen may fall into the pump and cause
extensive damage at start-up.
The base must be mounted to a leveled foundation, and final coupling alignment is done during installation.
(Refer to manual No.XXX, Installation Instructions, N.E.S. Company Vacuum Pumps and Compressors.)
NOTICE
SERVICE AND PARTS
SERVICE AND PARTS FOR NES VACUUM PUMPS ARE ASSURED THROUGH A WORLDWIDE
NETWORK OF SALES AND SERVICE OFFICES LISTED ON THE BACK COVER OF THIS MANUAL.
ANY REQUEST FOR INFORMATION, SERVICE, AND PARTS SHOULD BE DIRECTED TO THE
NEAREST NES SITE / FIELD OFFICE.
WHEN ORDERING REPLACEMENT AND SPARE PARTS, SERIAL NUMBERS AND PUMP SIZES

NBE O & M Document No. NES/NBE/O&M Page 2 of 43
MUST BE PROVIDED.
Serial number and pump size are located on nameplates riveted/fastened to the pump's casing/body. Parts must be identified
by index number and name. Refer to pump exploded view and legend found in this manual.
If the location of the nearest office is unknown, information may be secured directly from N.E.S. Company Inc. New Jersey
Head Quarters: 333 RT 46 W, BLDG: A, FAIRFIELD NJ 07004. Telephone number is 1-800-297-3550, Fax No. 973-933-
6322
WARRANTY
NES Company warrants that (1) the goods will be of the kind described on its acceptance of Buyer's order as modified by any
subsequent mutual agreement of the parties, (2) it will convey to Buyer good title to such goods, (3) such goods will be delivered
free of any lawful security interest or lien or encumbrances unknown to Buyer, and (4) such goods will be of merchantable
quality and free from defects in material or workmanship defects under normal use and prescribed maintenance for a period of
two (2) years from the date of shipment. The warranties specified shall also extend to goods manufactured by others and
supplied by N.E.S., unless such goods have been separately stated and quoted by N.E.S., in which case only the warranties in
clauses (1), (2) and (3) shall apply. NES MAKES NO WARRANTY, EXPRESS OR IMPLIED, AS TO THE
MERCHANTABILITY OF GOODS MANUFACTURED BY ITS SUPPLIERS AND SEPARATELY STATED AND
QUOTED HEREIN. N.E.S.'s warranty in clause (4) above shall not apply to goods of standard construction when handling
corrosive gases of using corrosive liquid compressant nor will clause (4) apply to goods which have been damaged, altered, or
negligently maintained after delivery. Buyer's exclusive remedy for N.E.S.'s breach of the warranties outlined in clauses (1), (2)
and (3) above shall be the replacement by N.E.S. of non-conforming goods with conforming goods, without extra cost to Buyer,
F.O.B. point of manufacture, with transportation prepaid to U.S. destination or domestic port, and Buyer's exclusive remedy
for N.E.S.'s breach of the warranty contained in clause (4) above shall be the repair by N.E.S. without charge, or the furnishing
by N.E.S. F.O.B. point of manufacture, with transportation prepaid to U.S. destination or domestic port of a part or item of
equipment to replace any part or item of equipment which is proved to have been defective; provided that (1) Buyer shall have
notified N.E.S. of any such breach not later than ten days after the expiration of two (2) years from the date of shipment of the
goods, and that (2) N.E.S. shall have the option of requiring the return of any defective material transportation prepaid to
establish a claim. N.E.S. shall in no event be liable for the Buyer’s manufacturing costs, lost profits, goodwill, expenses, or any
other consequential or incidental damages resulting from a breach by N.E.S. of any warranty. THERE ARE NO OTHER
WARRANTIES, EXPRESS OR IMPLIED, WHICH EXTENDED BEYOND THE WARRANTIES SET FORTH
HEREIN

NBE O & M Document No. NES/NBE/O&M Page 3 of 43
Manual Index
List of Sections
1. Safety Precautions ......................................................................................................................5
2. About this manual .....................................................................................................................5
3. How the N.E.S. Vacuum Pump works
3.1 Principle of Operation………………….…………………….…………...…………..…6
3.2 Operational parameters ………………………………………………………………….6
4. Installation
4.1 Uncrating, lifting, and moving Instruction ……………………………………….….….7
4.2 Piping Requirements …………………………………………………………………......7
4.3 Electrical Requirements ……………………………………….…………………….……7
5. Operation
5.1 Preparation for Initial Start-Up............................................................................................7
5.2 Liquid Compressant (Seal Water) .....................................................................................9
5.3. Draining and Flushing........................................................................................................12
5.4 Preliminary Inspection........................................................................................................13
5.5 Start-up and Operating Checks............................................................................................15
6. Troubleshooting
6.1 Detecting Troubles.................................................................................................................18
7. Preventive Maintenance
7.1 Periodic Maintenance............................................................................................................22
7.2 Six-Month Intervals...............................................................................................................24
7.3 Twelve-Month Intervals.........................................................................................................24
7.4 Bearing Lubrication .............................................................................................................24

NBE O & M Document No. NES/NBE/O&M Page 4 of 43
7.5 Stuffing Box Packing.............................................................................................................28
7.6 Shutdown Periods ................................................................................................................30
8. Disassembly, Reassembly, and Inspection
8.1 Pump Disassembly ..............................................................................................................31
8.2 Pump Reassembly ...............................................................................................................31
8.3 Pump Inspection ……………………...…………………………………………………..31
9. Technical data for NBE3 & NBE4
9.1 Spare Parts Lists ………………………………………………………………………….32
9.2 Dimensions and Specifications ………………………………………………………….35
9.3 Forces and torques on Flanges …………………………………………………………..36
9.4 Circuit Diagrams ………………………………………………………………………..37

NBE O & M Document No. NES/NBE/O&M Page 5 of 43
Section 1. Safety Precautions
1.1 Safety Precautions:
1. Wear appropriate personal protective equipment,
including safety glasses, lab coats, long pants, closed-
toe shoes, and gloves, when working with vacuum
pumps.
2. Store vacuum pumps on spill trays to prevent oil
spills and ensure proper containment.
3. Insulate running areas of the vacuum pump for
noise reduction, if necessary.
4. Dispose of used vacuum pump oils according to
prevailing EH&S (Environmental Health and Safety)
procedures.
Safety During Operation:
During continuous Operation of the pump, observe
the following safety precautions:
1. Ensure electrical cables/cords and power switches
are in good condition and free from defects or loose
connections.
2. Keep belt guards in place to prevent hands or loose
clothing from getting caught in the belt pulley.
3. Avoid operating pumps near containers of
flammable chemicals, flammable chemical wastes, or
combustible materials such as paper or cardboard.
4. Use appropriate vacuum tubing with thick walls,
avoiding thin Tygon-type hoses.
5. Avoid placing pumps in enclosed, unventilated
cabinets to prevent heat buildup and exhaust
accumulation.
6. Replace old tubing that has become crumbly to
maintain optimal performance.
7. Use the shortest length of tubing necessary to reach
the desired location.
8. Avoid using solvents that may damage the pump.
9. Always close the valve between the vacuum vessel
and the pump before shutting off the pump to
prevent vacuum oil from being drawn into the system.
10. Place a pan under the pumps to catch and collect
oil drips.
11. Regularly check oil levels and change the oil as
needed. Properly dispose of vacuum pump oil
contaminated with condensate following EH&S
procedures.
12. For oil-filled pumps with total recirculation
service, be aware that many vapors can condense in the
pump oil. Use cold traps or other appropriate
methods to trap evaporated materials and ensure
proper venting of the pump exhaust.
Safety During Service:
Before performing maintenance or service on a
vacuum pump or compressor, adhere to the following
safety precautions:
1. Stop the pump. Ensure all power switches and
circuit breakers are turned off. Use proper tagging to
indicate "Do Not Switch On."
2. Equalize the pump pressure with atmospheric
pressure by passing air into or out of the piping.
3. Empty or clear the service liquid from the pump
before opening it.
4. If the pump has operated with harmful liquids or
media, wash it thoroughly with an appropriate liquid
as specified in the Material Safety Data Sheet (MSDS)
of the operating fluid.
5. Maintain a record for each pump, documenting oil
change dates, bearing greasing dates, shaft rotation
dates, and maintenance schedules.
Please note that these rephrased instructions are
provided for clarity and understanding. It is important
to follow the specific safety guidelines and procedures
recommended by your organization and NES
Company Inc.
Section 2: About the Manual
The following document provides set-up instructions,
Operation, and maintenance information for your
NES NBE series of vacuum pumps. Please read the
complete document carefully before operating your
pump. If you need further assistance in understanding
the details in this document or the pumps, please call

NBE O & M Document No. NES/NBE/O&M Page 6 of 43
NES Company Inc. at 1-800-297-3550 or email at
[e-mail]
When contacting NES Company Inc., please be ready
with the following information:
1. A reference number to locate your pump in NES
Company Inc.’s system.
2. The nature of the process in which the pump is
used.
3. The steps taken so far in the installation and set-up
of the vacuum pump.
4. Please ensure that the manual has been completely
read by all the people involved in operating the pump.
Section 3: How the N.E.S. NBE pump
works
3.1 Principle of Operation
The NES NBE series pumps are single-stage liquid
ring vacuum pumps which rely on the rotation of an
impeller to create a liquid ring seal within the pump
chamber, which enables the pumps to create a
vacuum. Initially, the pump is filled with a sealing
fluid, typically water or another compatible liquid,
which acts as both a sealant and a compressing
medium. The impeller is mounted on a rotating shaft
driven by an external motor, starts to rotate within the
pump chamber generating a centrifugal force which
impeller pushes the sealing fluid towards the outer
periphery of the pump chamber forming a concentric
liquid ring. As the impeller continues to rotate
towards the discharge port, the space between the
impeller blades gradually decreases due to the presence
of the sealing fluid. This compression action causes
the gas to be compressed against the sealing fluid, and
the resulting gas-fluid mixture is discharged through
the discharge port. The sealing fluid plays a crucial role
in the Operation of the NES NBE Series pumps,
ensuring effective sealing, gas compression, heat
dissipation, and contaminant removal. The fig. 1
shows a typical NBE series liquid ring vacuum pump.
Fig. 1. NBE Series Liquid Ring Vacuum Pump
3.2 Operational parameters
The NES NBE series of liquid ring vacuum pumps
comprise of the sizes ranging from NBE1-152 to
NBE4-7000. The increasing number indicates
increasing suction capacity. The single stage NBE
series vacuum pumps are designed to operate with dry
and moist gases with inlet temperature min. 32 °F and
max. 176 °F, inlet pressure up to 28” Hg. Some pumps
in this series operate to 23” Hg. For more details,
please refer to the NES NBE Series Data Sheet, pump
drawings, and performance curves.

NBE O & M Document No. NES/NBE/O&M Page 7 of 43
Section 4: Installation
4.1 Uncrating, lifting, and moving
instructions:
After the pump is received, it is important to ensure
compliance with the listed items on the packing slip.
If there is any visible damage, such as dents or
scratches, immediate notification should be made to
the freight carrier and NES Company Inc. It is
important to note that NES does not take
responsibility for damage that occurs during transit
and such damage will not be covered under warranty.
Follow the instructions below when uncrating the
pump.
1. Gently remove the crate lid and packaging material.
2. Dispose of the packaging material properly to avoid
any personnel injuries caused by sharp nails or pointed
objects.
3. Obtain information on the total weight, maximum
outside dimensions, and location of lifting points. If
this information is not available, contact NES
Company Inc.
4. When lifting and moving the pump or pump
assembly, ensure it remains horizontal to the ground.
5. Avoid exerting pressure on the seal water piping,
valves, and other delicate components in the system
with the lifting ropes.
4.2 Piping requirements:
Please confirm that the piping matches the system
drawings provided by NES Company Inc. Also, check
that the pipe sizes and configuration match the
connection sizes on the pump/system. At the
discharge, ensure that there is no back pressure on the
pump by piping it horizontally into a
separator/silencer. NES Company Inc. suggests
incorporating valves and gauges on the sealing fluid
piping and inlet piping. If possible, link the pump
drain connection to the main discharge drain line and
install a gate valve. Ensure the valve remains closed
during Operation and open it when the pump is
turned off to facilitate the flow of seal water out of the
pump.
4.3 Electrical requirements:
Always refer to the motor nameplate to confirm the
motor horsepower and voltage, ensuring it matches
the electrical power source. Consult the relevant data
sheet for the wiring specifications of process valves and
actuators installed in the system.
Section 5: Operations
5.1 Preparation for Initial Start-Up
When commissioning the machine, especially after a
drain or when it is dry, the following steps should be
followed:
5.1.1 Initial Technical Status:
1. Please ensure all lines for pumped gases/vapors are
correctly connected.
2. Close all shut-off fittings and avoid installing shut-
off or non-return fittings on the discharge side.
3. It is necessary to drain the preservative liquid from
the machine and its disposal according to applicable
regulations.
5.1.2 Operating liquid:
Appropriate volume of the operating liquid must be
poured and adjusted as specified in Section 5.3. This is
followed by opening the shut-off valve for the
operating Liquid. Depending on the size of the
machine, this can be done approximately 5 to 15
minutes before the start-up. The machine's working
area should be filled up to the point of overflow on the

NBE O & M Document No. NES/NBE/O&M Page 8 of 43
discharge connection or the welding neck flange (if
available for partial draining) on the discharge side. It
is essential to ensure that the operating liquid level in
the machine's working space does not exceed the shaft
center during start-up.
WARNING!
Improper usage of the machine can lead to severe
or even fatal injuries!
It is essential to carefully read and adhere to the safety
precautions outlined in section 1. Failure to do so will
prohibit any work with or on the machine.
Risk of injury from rotating parts (impeller,
shaft):
There is a danger of limb amputation, entanglement of hair
and clothing. Exercise caution!
Risk from gauge pressure and vacuum:
There is a risk of sudden fluid escape causing skin and eye
injuries and entanglement of hair and clothing. Be
cautious!
Risk from escaping fluid:
There is a risk of burns, scalding, slipping, and falling. Take
precautions!
Commissioning and Operation should only be conducted
under the followingconditions: •All lines and fittings must
be properly mounted on the connections in the end shield.
Keep unused connections sealed with provided sealing
devices (plugs, covers). • Ensure the machine is fully
assembled. • Verify the motor rotation direction. • The
operating liquid level should be up to the middle of the
shaft, with the operating liquid supply connected and
checked. • The housing should not be overfilled. • Check
the fill level in the pump housing before starting. • Verify
the condition of armatures and regulating devices on the
suction and discharge sides. • Ensure suitable
environmental conditions. • Check and align the drive
elements (coupling, belt drives). • Align and ground the
machine. • Close unused connections with blind flanges. •
Keep inspection covers on the end shields closed.
WARNING!
Danger from gauge pressure and vacuum:The
machine poses a significant risk of bursting parts, sudden
fluid escape (resulting in skin and eye injuries), and
entanglement of hair and clothing when subjected to
excessively high pressures. Extreme caution is required!
The machine must not be operated with a blocked inlet or
discharge side!
Before initiating Operation, ensure the following
precautions: • Remove any closures from the inlet and
discharge connections. • Ensure all pipes are properly
connected. • Ensure that shut-off devices (e.g., valves, gate
valves, etc.) in the lines are open. • Prevent the connections
and lines from clogging with deposits or solid materials. •
When handling fluids containing solid materials, connect
suitable screens or filters upstream of the machine. • Be
aware that air saturated with water vapor, containing
droplets, emerging from the pressure side can cause icing
and create a slip hazard during winter. • Take into
consideration that air saturated with water vapor,
containing droplets, emerging through the roof can cause
icing, leading to additional roof loads and associated risks.
5.1.3 Shaft Seal:
For commissioning new machines with stuffing boxes
having internal liquid supply, the stuffing boxes are
usually adjusted during the factory test run. However,
during commissioning, tightening of stuffing box
packing by tightening each stuffing box gland by one
screw rotation may be required. For restarting
machines that were previously operated, the stuffing
boxes should be readjusted. For stuffing boxes with
external liquid supply, open the shut-off valve for the
sealing liquid to moisten the stuffing box packing.
These steps ensure a proper commissioning process
for the machine. Please refer to Table 1 for types of
mechanical shaft seals required for different NBE
pump models.

NBE O & M Document No. NES/NBE/O&M Page 9 of 43
For different types of mechanical seals and their
respective sealant supplies, the following steps should
be taken during commissioning:
1. Single-Acting Mechanical Seal with Internal Sealant
Supply:
Before starting the pump confirm that the interior of
the machine is filled with operating Liquid
approximately up to the shaft center. This prohibits
the mechanical seal from running dry.
2. Single-Acting Mechanical Seal with External
Sealant Supply:
Shortly before starting the machine opens the shut-off
fitting for the sealing liquid. This prevents drying of
mechanical seal and maintains the liquid level in the
machine at an appropriate level.
3. Double-Acting Mechanical Seal:
Just before starting the machine, open the shut-off
valve for the sealing liquid. This will stop the
mechanical seal from running dry.
4. Adjustment of Volumetric Flow or Feed Pressure of
Flushing/Sealing Liquid:
Use a volume flow meter or a pressure gauge to check
and adjust the values of the flushing or sealing liquid.
This ensures that the desired volumetric flow or feed
pressure is maintained.
It is important to carefully follow the specific
instructions provided by the manufacturer for the
mechanical seal and sealant supply configuration of
your machine. These steps help prevent the
mechanical seal from running dry, ensuring its proper
functioning and longevity.
Table 1: Types of mechanical shaft seals
5.2 Liquid Compressant (Seal Water)
The operating Liquid, often referred to as the sealing
Liquid or liquid compressant, plays a crucial role in
the operation of liquid ring machines like vacuum
pumps and compressors. It helps create a liquid ring
within the housing, which acts as a seal between the
impeller and the housing, preventing direct contact
between the gas being handled and the impeller. The
sealing fluid is typically fresh water at a temperature of
60F. Refer to table 2. below for seal water flow rate
information. Alternatively, other fluids such as diesel,
mineral oil, and methanol can be used as sealing fluid
depending on the process requirements and
availability. When using a discharge separator, it is
important to ensure that the seal fluid level always
remains below the centerline of the pump during
Operation. This prevents any back pressure caused by
the discharged seal fluid.
WARNING!
When working with hazardous gases or operating liquids,
it is imperative to prevent any unintended escape of gases
or operating fluids in the event of an unforeseen reduction
in seal function. This can be achieved by employing
appropriate shaft sealing methods, such as mechanical seals
with external supply, to ensure the integrity of the system.
Type
Shaft Seals
NBE3/4… - … 3
Stuffing box with external
liquid feed (external sealant
supply)
NBE3/4… - … 4
Stuffing box with external
liquid wetting (standard)
NBE3/4… - …
5…9
Mechanical seals

NBE O & M Document No. NES/NBE/O&M Page 10 of 43
CAUTION!
Risk of machine damage from escaping liquid spray!
When the feed pressure exceeds 4.35 psi above the discharge pressure, there is a high possibility of liquid spray escaping. It is
crucial to ensure that the feed pressure of the sealing liquid does not exceed 0.3 bar [4.35 psi] above the discharge pressure!
Failure to properly operate the machine with sealing liquid can result in the rapid destruction of the mechanical
seal!
DO NOT start the machine if the seal area is not filled with sealing Liquid, not even for a moment (e.g., to check the rotating
direction)!
If necessary, ensure the sealing space is properly bled!
Incorrect feed pressure of the flushing/sealing liquid can cause faults and damage!
Due to low feed pressure:
The seal area may not receive an adequate amount of sealing liquid.
The mechanical seal may be damaged.
If the feed pressure is too high, then excessive wear on the mechanical seal will occur.
Always ensure that the feed pressure of the flushing/sealing liquid is properly adjusted to avoid these issues!
Compressor:
Volumetric flow of operating Liquid in GPM dependent on compression pressure in PSIG (tolerance
approx. ± 10 %)
Type 2
NBE3/4
…
30. 32. 40. 42. 50. 52. 60. 62. 67. 72.
2.7 PSIG
24
26
26
26
26
26
26
26
26
26
5.6 PSIG
31
35
44
52
55
63
66
77
88
97
8.5 PSIG
40
47
59
74
85
99
110
128
145
172
11.4 PSIG
50
57
75
99
114
134
150
126
211
247
14.3 PSIG
62
69
92
121
143
170
194
229
269
317
17.2 PSIG
71
79
108
145
171
204
233
273
326
392
20.1 PSIG
82
90
125
--
200
--
277
--
--
--
23.0 PSIG
--
--
141
--
229
--
319
--
--
--
Table 2: Operating Liquid Flow rate
Vacuum pump:
Volumetric flow of operating Liquid in GPM dependent on inlet pressure in PSIA (in HgA) (tolerance
approx. ± 10 %)
Type NBE3/4
…
30.
32.
40.
42.
50.
52.
60.
62.
67.
72.
2.9 (5.9)
23
30
41
56
77
93
106
130
152
182
3.63 (7.4)
24
31
43
58
78
95
109
133
156
186
4.35 (8.9)
25
31
44
60
81
98
112
136
160
192
5.8 (11.8)
23
29
40
54
73
89
101
123
145
174
7.25 (14.8)
19
25
35
47
63
78
89
108
126
151
8.7 (17.7)
16
21
29
40
53
65
75
90
106
127
10.15 (20.7)
13
17
23
32
44
53
60
74
87
104
11.6 (23.6)
11
13
19
26
34
42
48
58
68
82

NBE O & M Document No. NES/NBE/O&M Page 11 of 43
5.2.1 Function of Liquid Compressant
The liquid compressant in a liquid ring machine, such
as vacuum pumps, performs several important tasks.
Here are the key functions of the operating Liquid:
1. Formation of the liquid ring: The primary function
of the operating liquid is to form a liquid ring within
the housing of the machine. This liquid ring is crucial
to the principle of Operation of the machine. It serves
as a rotating seal, creating a barrier between the
impeller and the housing, and facilitating the
compression of gases or the creation of a vacuum.
2. Sealing off the gap: The operating liquid acts as a
sealing agent between the impeller and the port plate
or housing. It fills the gap between these components,
preventing direct contact between the gas being
handled and the impeller. This sealing action helps
maintain the efficiency and performance of the
machine by minimizing gas leakage and optimizing
compression or vacuum generation.
3. Cooling: Another important task of the operating
liquid is to provide cooling for the machine. During
Operation, the compression of gases or the creation of
a vacuum can generate heat. The operating Liquid
helps absorb and dissipate this heat, preventing
overheating of the machine. Efficient cooling ensures
the longevity of the components and contributes to
the overall performance and reliability of the system.
4. Shaft seal: The operating liquid also acts as a seal for
the shaft of the machine. It helps prevent any gas
leakage along the shaft, ensuring that the gases being
handled are contained within the system. By providing
an effective shaft seal, the operating Liquid helps
maintain the desired pressure differentials and
prevents the loss of gases or vapors.
These tasks collectively contribute to the efficient and
reliable Operation of the liquid ring machine. The
operating liquid plays a critical role in maintaining
proper sealing, cooling the system, and ensuring the
effective functioning of the shaft seal, all of which are
vital for optimal performance and longevity of the
machine.
5.2.2 Characteristics of Liquid Compressant
The properties of the operating liquid in a liquid ring
machine are important for ensuring its safe and
efficient Operation. Here are some key properties and
considerations:
1. Non-flammable, non-explosive, non-aggressive,
and non-toxic: The operating liquid should be chosen
to avoid any risks of fire, explosion, or harm to
personnel. It should not have aggressive or corrosive
properties that could damage the machine or pose
safety hazards. Additionally, the operating liquid
should be non-toxic to prevent any health risks.
2. Water as a common choice: Water is commonly
used as an operating liquid due to its availability, low
cost, and suitable properties for many applications. It
is non-flammable, non-toxic, and generally non-
aggressive. However, water quality and impurities
should be considered.
3. Filtration to remove impurities: To maintain the
proper functioning of the liquid ring machine,
suitable filters or sieves should be installed upstream of
the machine to remove impurities. This helps prevent
the entry of abrasive or erosive substances into the
machine, which could damage the components or
reduce efficiency.
4. Maximum permissible dissolved solid quantity: It is
recommended to limit the amount of dissolved solids
in the operating Liquid. A maximum permissible
dissolved solid quantity of 200 parts per million (ppm)
is often used as a guideline. Excessive dissolved solids
can lead to scaling, fouling, and reduced performance.
5. Managing calcium content and lime deposits: If the
operating liquid has a high calcium content, there is a

NBE O & M Document No. NES/NBE/O&M Page 12 of 43
risk of lime deposits forming within the machine,
affecting its performance. In such cases, appropriate
measures should be taken, such as the addition of
water softeners or the installation of an ionic
accelerator. These measures help mitigate the risk of
lime deposits and ensure smooth Operation.
It is essential to select an operating liquid that meets
the specific requirements of the liquid ring machine
and the application. Considering the properties of the
operating liquid and taking necessary precautions
helps maintain the machine's performance, longevity,
and safety.
CAUTION!
Risk of Damage Due to Calcification
Over time, hard lime layers can develop and eventually
break open, leading to potential erosion damage to
components. It is crucial to implement preventive
measures to continuously prevent the formation of
lime deposits or perform regular removal procedures.
WARNING!
Risk of Environmental Damage
If the operating liquid used is harmful to the
environment, it is crucial not to drain it off into the
open. Instead, it must be circulated in a closed circuit
with forced circulation to prevent any potential
environmental damage.
5.2.3 Types of Liquid Compressant
There are two variants of the operating Liquid in
liquid ring machines depending on the internal
routing and cooling requirements:
1. Normal Cooling (Economy Circulation): This is
the standard design for the machine. In normal
cooling, a portion of the operating liquid that is
discharged from the machine is recirculated back into
the system. This recirculation helps maintain the
desired operating liquid flow and temperature. The
volumetric flow rate of the operating liquid
corresponds to the values specified in the machine's
specifications.
2. Increased Cooling (Refrigeration Circulation):
This design is specific to certain vacuum pump models
and is the standard design for compressors. Increased
cooling is used when operating conditions are
unusual, such as handling gases at high temperatures
or when higher suction capabilities are required. In
this case, the operating liquid is completely removed
from the machine and replaced with new, cooler
Liquid. The internal partial circuit is closed, and the
necessary adjustments, such as mounting plugs, are
made for permanent use. The volumetric flow rate of
the operating liquid is doubled compared to the
specifications for vacuum pumps mentioned in the
specifications.
The choice between normal cooling and increased
cooling depends on the specific requirements and
operating conditions of the liquid ring machine.
Consulting with the manufacturer or a qualified
service provider can help determine the most suitable
variant for a given application.
5.3 Draining and Flushing
Draining: For draining and flushing the machine,
open the shut-off valve.
• Locate the shut-off valve on the drainpipe connected
to the draining and flushing connection.
• Place a suitably large catch container beneath the end
shields of the machine.
• Unscrew the plug to completely drain the liquid
from the end shields.
After fully draining the machine:
• Close the shut-off valve for draining and flushing.
• Reinstall the plug in its original position.

NBE O & M Document No. NES/NBE/O&M Page 13 of 43
• If the pump has a mechanical seal, follow the
instructions provided in the mechanical seals manual
to completely drain the liquid from all seal housings.
Prior to initiating the pump after installation and
alignment, commence with a preliminary inspection.
Remove the drain plugs from the pump and allow the
seal water line to be opened, enabling water to enter
the pump. It should be noted that prior to shipping,
the pump undergoes flushing with a water-soluble
preservative to prevent any seizing during
transportation. Allow the water to flush out all traces
of preservative through the drains. Subsequently,
cease the supply of seal water and securely close the
drains using pipe thread compounds.
CAUTION!
There is a risk of slipping and falling due to escaping
Liquid. When draining the machine, it is essential to
use appropriate catch containers to prevent liquid
from spilling onto the floor or work area.
Flushing: Regular cleaning is recommended to
remove any foreign bodies that may have accumulated
in the liquid ring. This can be done by temporarily
opening the valves in the drain linear unscrewing the
plugs for total draining during storage periods. Refill
the system with clean water for the flushing process.
Flush out dirt during running operation: If the
operating liquid becomes contaminated and there is a
possibility of erosive wear, it is important to pipe and
connect the end shield holes, closed by plug, to an
external discharge. It is recommended to use piping
with adjustable valves. The amount of drained fluid in
the lobe should be adjusted to ensure it does not affect
performance. The drained Liquid should be
compensated through the seal water supply.
Removal of lime deposits: If deposits of lime are
present, the machine needs to be treated with a
decalcifier as part of maintenance. The necessary
intervals for decalcification depend on the lime
content of the operating Liquid. It is recommended
that the intervals are not less than half a year to avoid
material damaged calcification occurring at a high
rate, it is advisable to implement continuous
treatment for the machine.
Type: Recommended options include phosphoric
acid (in a solution of 15 parts acid to 17 parts water) or
ethanoic acid (in a solution of 20 parts acid to 100
parts water).
Filling Amount: The filling amount should
correspond to the volume of the entire machine. The
specific employed method should be selected based on
the resistance of the materials in the machine. Follow
the safety data sheets of the chemicals used and adhere
to local disposal ordinances. It is recommended to
have authorized personnel from NES Service conduct
the decalcification process. NES also recommends
contacting Dynamic Descaler to conduct the
descaling process.
WARNING!
When using compressed air for cleansing, ensure that you
take appropriate protective measures such as wearing
protective glasses and a protective breathing mask to
safeguard against potential hazards.
When utilizing chemical cleansers, it is crucial to adhere to
the warning and application instructions outlined in the
corresponding safety data sheets. Additionally, ensure that
the chemical agents employed are compatible with the
materials and components involved.
5.4 Preliminary Inspection
Conduct the following preliminary inspections prior
to initiating the pump:
WARNING!
Ensure all the following steps are performed in the
specified order to ensure personal safety and
equipment protection.

NBE O & M Document No. NES/NBE/O&M Page 14 of 43
1. Disconnect all power sources from the driver unit
to prevent accidental starting.
2. Verify that all drain plugs on the pump are properly
installed.
3. Prime the pump manually with the liquid
compressant until there is a flow from the overflow.
4. Examine the separator, receiver, and heat exchanger
(if applicable) to confirm that all shipping plug
protectors have been removed and all open
connections have been properly plugged or piped.
5. Look carefully at all piping to ensure correct
connections to the pump and its basic system,
following the installation drawings provided by
N.E.S. Ensure that all piping is of the accurate size,
securely connected, and sufficiently supported.
6. Inspect the vacuum pump and drive hold-down
bolts, as well as the base or soleplate foundation bolts,
to ensure they are tight. Shim the base if required.
7. Check all other significant operational component
connections related to the pump, following the
recommendations of respective equipment
manufacturers.
8. Examine all pump control components (control
valves, gauges, etc.) to verify their locations according
to the N.E.S. installation drawings. Ensure that these
components are correctly positioned in the piping
scheme to achieve proper flow and functional
Operation.
9. Check the pump inlet to confirm that the inlet
screen and clean-out connections are properly
installed and free from tools, equipment fragments,
and debris.
10. Confirm that the liquid discharge connection is
clear of any obstructions.
11. Disconnect the coupling or V-belt guard and
manually rotate the pump shaft in the specified
direction indicated on the drive end casing of the
pump. The direction of rotation is marked by an
arrow on the pump body and is illustrated in the
installation drawing.
Ensure the pump shaft rotates freely. If the pump
shaft is stuck and cannot be freed by manual rotation,
contact your N.E.S. representative for assistance.
CAUTION!
do not try to free a binding or bound pump shaft by
applying power to the drive motor. Such action can result
in severe damage.
never operate the pump without sufficient priming and
liquid seal flow. high liquid seal supply pressures do not
guarantee sufficient flow. Please verify flow rates by
consulting an N.E.S. representative and ensure flow from
the vacuum pump discharge (or water trap silencer).
1. By keeping the main supply valves open and the
pump primed, gently bump the drive motor for the
pump to verify the correct direction of shaft rotation.
WARNING!
Ensure that the coupling or V-belt drive is protected with a
guard before starting the drive motor. 2-5 Start-up and
operating checks.
Once the preliminary inspection and pre-operational
checks have been completed, start the pump, and
perform the following pump operation checks:
WARNING!
If the pump is supposed to be checked a system, it is
important to inform the relevant plant personnel before
putting the pump into Operation, particularly if it is the
first time. starting a system without prior notice can pose a
risk of personal injury.
Note: Refer to the Troubleshooting section (Section
6) if any operational difficulties arise during the
following steps.
i) Verify that the pump and system have adequate
priming, and then activate all main water supply
sources to the pump or heat exchanger.

NBE O & M Document No. NES/NBE/O&M Page 15 of 43
ii) Once the water supply sources are activated and all
personnel and equipment are safely away from the
pump system, turn on the drive motor.
Note: If pump operation becomes unstable, resulting
in increased vibration levels and decreased pumping
volume, shut down the system immediately and
determine the cause.
iii) While the pump is stabilizing at the required inlet
vacuum, inspect the flow of the liquid seal (water) to
the pump. Ensure that the liquid seal is flowing out of
the water trap silencer drain.
iv) Continuously monitor the temperature of the
pump casing during the start-up procedure. If the
temperature rises quickly or reaches 25°F (14°C) or
more above the liquid compressant temperature, shut
down the unit immediately and determine the cause.
v) After starting the pump, monitor the temperature
of the bearing bracket until the temperature stabilizes
for a minimum of 30 minutes.
CAUTION!
If the temperature of a bearing bracket is more than 30°f
(17°c) higher than the pump casing temperature, shut
down the pump immediately and identify the cause.
Caution: if there is abnormal bearing noise, vibration,
odor, or smoke, shut down the pump immediately and
determine the cause.
vi) Inspect the pump for vibration and noise. Excessive
vibration and noise indicate an abnormal condition for an
N.E.S. pump. Shut down the pump immediately to avoid
further damage and identify the cause.
vii) Verify the speed (R.P.M.) of the pump shaft rotation
by removing the nameplate cap from the fixed bearing
outer cap and using a tachometer with a shaft extension, if
required. Evaluate the measured speed with the rated speed
specified for the pump. The rated operating speed and
capacity can be found in the purchase specifications or
obtained by consulting your N.E.S. Representative.
5.5 Start-up and Operating Checks
5.5.1 Start-up
To proceed with the commissioning process, please
follow these steps:
1. The shut-off valve in the inlet pipe should be
opened first.
2. If your machine is equipped with a mechanical seal
with an external sealant supply, open the shut-off
valve for the sealing liquid.
3. Switch on the drive motor to start the machine.
4. Adjust the shut-off valve for the seal water as
follows:
If you are using a method with volume flow
measurement, open the shut-off valve for the
operating Liquid wide enough for the volume flow
meter to show the required volumetric flow.
Once the final inlet pressure is reached, adjust the
volumetric flow of the operating liquid to the correct
value.
Monitoring the volume flow using a flow meter and
adjusting the operating liquid flow rate accordingly
helps maintain the proper functioning and
performance of the machine during commissioning.
If you encounter any difficulties or require further
assistance during the commissioning process, it is
advisable to contact the NES support or service
department for guidance.
Method for pressure measurement during start-up:
Perform this step when the pressures on the inlet
connection and discharge connection are equal in the
start-up state.
1. Adjust the shut-off valve for the liquid compressant
so that the pressure gauge indicates approximately
14.5 psia (0 psi gauge pressure) in the start-up state.
2. As the final inlet pressure is reached during
Operation, the pressure gauge may indicate a different
value, ranging from approximately -2.9 to +1.45 psi

NBE O & M Document No. NES/NBE/O&M Page 16 of 43
gauge pressure. This variation depends on the internal
operating liquid connection.
Shaft seal:
For internal liquid supply packing, no special
measures are required. For stuffing boxes with internal
liquid wetting, little to no leakage can occur.
For stuffing boxes with external liquid supply, adjust
the stuffing boxes and the volumetric flow and feed
pressure of the sealing Liquid. Leakage can occur at
the stuffing boxes, and it is important to ensure that
the leakage is within acceptable limits (a few drops per
second).
CAUTION!
Risk of shaft damage:
If there is excessive Liquid in the machine interior, the
pressure on the shaft can become too high and lead to
damage during start-up.
The operating liquid level in the working space of the
machine must not exceed the shaft center during start-
up.
Take the following measures:
1. Ensure that the operating liquid level in the working
space is properly adjusted immediately before start-up.
2. Avoid any significant additional accumulation of
liquid (operating liquid or sealing Liquid) in the
working space of the machine between the preparation
for commissioning and start-up.
5.5.2 Operational Checks
During pump start-up, it is crucial to perform the
following checks to ensure optimal Operation,
prevent pump wear, and avoid breakdowns:
1. If the pump exhibits excessive vibration levels or
fails to generate vacuum and loses volume during start-
up, promptly shut down the pump to prevent further
damage.
2. Investigate and identify the root cause of the
problem before running the pump again. Potential
issues may include a loose foundation, improper
alignment, insufficient sealing fluid, and
malfunctioning valves or switches, among others. For
detailed troubleshooting guidance, see section 6.
3. Once the pump stabilizes, regularly monitor the
temperature of the pump body, bearings, motor, and
cooling water to ensure they remain within acceptable
limits.
4. If any of the components experiences a sudden
temperature rise, immediately shut down the system
and inspect the temperature of the inlet seal water and
heat exchanger cooling water. Verify that the motor is
properly wired and not overloaded.
5. When the pump is running smoothly, adjust the
gland nuts to achieve a drip rate of 1-2 drops per
second. This controlled drip rate helps to keep the
packing cool, reducing wear and prolonging the
pump's lifespan.
6. Continuously monitor the operating vacuum and
corresponding air capacity, and ensure the pump is
safeguarded against sudden load spikes by employing
a properly calibrated vacuum relief valve.
Additionally, take precautions to prevent liquid
carryover into the pump, as even though the pumps
are resilient, minimizing carryover is advisable for
optimal performance.
WARNING!
Rotating Parts and Pressure/Vacuum
Hazards:
Be aware of the dangers associated with
rotating parts, such as the impeller and shaft,
which can cause severe injuries, including
cuts, amputations, and entanglement of hair
and clothing.
Understand the risks related to gauge pressure
and vacuum, which can result in sudden fluid
escaping, leading to skin and eye injuries, as
well as the potential for hair and clothing to be
forcefully pulled in.

NBE O & M Document No. NES/NBE/O&M Page 17 of 43
Recognize the dangers of escaping fluids,
which can cause burns or scalding, as well as
slippery surfaces that may result in slips and
falls.
Preparatory Measures:
1. Shut down the machine and ensure it is secured to
prevent accidental restart.
2. Place warning signs on the system controller and
control elements, informing others that maintenance
work is in progress and that the machine should not be
switched on.
3. Allow the machine to come to a complete stop and
take note of any run-on time.
4. Shut off lines, perform pressure relief, and drain
excess liquid to eliminate gauge pressure or vacuum in
the system before proceeding with any further work.
B. Components Removal:
1. Do not remove the following components until
after the machine has come to a complete stop, the
lines have been shut off, and the pressure has been
released:
2. Lines and blind flanges on the inlet and discharge
connections.
3. Inspection covers on the end shields.
4. Lines, fittings, and closures (plugs, covers) on the
connections in the end shield.
5. It is crucial to strictly adhere to these safety measures
and follow the specific instructions provided by the
manufacturer to ensure the safety of individuals
working with or on the machine. Failure to do so can
result in severe injuries or accidents.
5.5.3 Shut down.
To shut down the machine, follow these steps:
1. Close the shut-off valve for the liquid compressant,
and instantly switch off the drive motor.
2. For different types of shaft seals, follow the
corresponding steps:
❖For stuffing boxes with internal liquid supply, no
special measures are needed.
❖For stuffing boxes with external liquid supply,
close the shut-off valve for the sealing liquid.
❖For single-acting mechanical seals with external
sealant supply, close the shut-off valve for the
flushing/sealing Liquid shortly after the machine
is switched off.
❖For double-acting mechanical seals with external
sealant supply, close the shut-off fitting for the
sealing liquid after the machine is switched off.
❖Close the shut-off valve in the inlet pipe.
❖Wait until the machine and drive elements (drive
motor, gear unit, coupling) have come to a
complete stop before proceeding with further
measures.
If there is a risk of frost, additional steps should be
taken to drain the liquid from the machine, liquid
separators, and pipes. The lines may need to be
disassembled to ensure complete draining. For
machines with mechanical seals, the liquid should be
completely drained from all seal housings.
WARNING!
•Shutdown the machine and ensure it is secured to prevent
accidental power-on.
•Display a warning sign on the system controller and
control elements, stating "DANGER! Maintenance work
on vacuum pump/compressor! Do not switch on!"
•Wait for the machine to come to a complete stop,
considering the run-on time.
•Shut off all lines, ensuring pressure relief and drainage of
excess Liquid.
•Confirm that there is no gauge pressureor vacuum present
in the lines, tanks, etc., that are to be opened.
•Particularly, do not remove the following components
until after the machine has completely stopped, the lines
have been shut off, and the pressure has been released:
•Lines and blind flanges on the inlet and discharge
connections.
•Inspection covers on the end shields. Lines, fittings, and
closures (plugs, covers) on the connections in the end
shield.

NBE O & M Document No. NES/NBE/O&M Page 18 of 43
Section 6: Troubleshooting
6.1 Detecting Troubles
Pump does not start, although motor is switched on
Possible causes
:
Solutions:
Electric connections are interrupted
Inspect the electrical fuses, terminals, and cables
The pump motor does not start but produces a noisy vibration
Possible causes:
Solutions:
One or several electrical connections could be
interrupted
Inspect the electrical fuses, terminals, and cables.
The impeller might be obstructed Disassemble the machine to drain, decalcify, and clean the
machine.
Reassemble the machine again.
Verify the clearance between the impeller, rotor, and housing to
ensure proper adjustment
The main circuit breaker trips immediately after the machine is started
Possible causes:
Solutions:
There is a short-circuit in the motor winding
Inspect the motor winding
The motor is experiencing an overload
Decrease the flow rate of the seal liquid
The counter-pressure at the discharge
connection is excessively high
Reduce the counter-pressure
The liquid flowrate is adjusted or set too high
Decrease the quantity of Liquid
The main circuit breaker trips immediately after the machine is started
Possible causes:
Solutions:
There is a short-circuit in the motor winding
Inspect the motor winding
The motor is experiencing an overload
Decrease the flow rate of the seal liquid
The counter-pressure at the discharge
connection is excessively high
Reduce the counter-pressure
The liquid flowrate is adjusted or set too high
Decrease the quantity of Liquid
Making abnormal noise or squealing
Possible causes:
Solutions:
The machine experiences cavitation Introduce air into the feed, install a valve on the inlet connection,
or use an anti-cavitation valve
The flow rate of the seal liquid is excessive
Verify and adjust the flow rate of the sealing Liquid to ensure
proper sealing. Reduce the flow rate if it is too high
Might be bearing making noises
Need to change the bearings
There is leakage of Liquid between the housings
Possible causes:
Solutions:
The sealant may be damaged
Replace the sealant

NBE O & M Document No. NES/NBE/O&M Page 19 of 43
Screws may be loose
Verify if the screws are tightened using the appropriate tightening
torques
There is leakage of Liquid between the housings
Possible causes:
Solutions:
The sealant may be damaged
Replace the sealant
Screws may be loose
Verify if the screws are tightened using the appropriate tightening
torques
Machine damaged due to rough running
Possible causes:
Solutions:
The base frame experiences vibrations
Add base concrete into the base frame and, if required, the gear
unit base
The machine experiences vibrations
Verify the alignment and mounting of the machine
The pipes experiences vibrations
Inspect the mounting of the pipes
There is a pulsing gas flow
Ensure proper installation of the piping on the suction side and
monitor for water slugs through the inlet piping.
Also, examine the non-return fittings
Excessive Liquid on the inlet side, in the end
shield, and around the rotor
Excessive operating liquid: Adjust the throttle to reduce the flow
of operating Liquid.
Inlet seal flow rate is too high: Install a pre-separator in the inlet
pipe to separate excess Liquid
The separator is positioned at an elevated
height
Position a pre-separator at a lower level in the inlet pipe to regulate
the flow of Liquid.
Operating liquid quantities are too high: Reduce the amount of
operating Liquid used in the system
High power consumption leading to machine overload
Possible causes:
Solutions:
Calcification or deposits are present
Remove calcification or deposits from the machine through
decalcification.
If necessary, disassemble and clean the machine Soften the seal
liquid to prevent calcification or deposits
Measuring devices display incorrect readings
Inspect the measuring devices and calibrate them if needed
Discharge pressure is too high
Examine the system.
Pulsating power consumption
Check the operating liquid quantity.
Inspect the non-return fittings.
Reduce the inlet seal flow rate by installing a pre-separator in the
inlet pipe
Separator placed too high
If the separator is placed too high, reposition it to a lower level.
Operating liquid quantities may be too high: Adjust the operating
liquid quantities to an appropriate level

NBE O & M Document No. NES/NBE/O&M Page 20 of 43
Impeller frictions
Rectify the impeller gap by opening the inspection cover (if
present) and checking the impeller gap
Packing is tightened too securely
Readjust the packing gland assembly
High solids ingestion through the inlet pipe
Regularly flush the housing and consider installing a dirt trap in
the inlet pipe.
Improve the water quality if needed
Motor protection enabled If no faults are detected on the machine, check the motor
protection settings, and consider using a motor protection unit
with a higher operating current if necessary.
Motor size is inadequate: If no faults are found on the machine,
evaluate the motor size, and consider using a drive motor with a
higher output if needed
Housing Erosion
Assess the material's wear resistance and consider installing a filter
in the operating liquid feed pipe. If required, replace the housing
with a higher-quality design
Maximum permitted pressure difference
surpassed
Exclude unnecessary throttle points, such as closed lines or
incorrectly adjusted gate valves, on the inlet and/or discharge side
to avoid exceeding the maximum pressure difference
Too Low Capacity
Possible causes:
Solutions:
Presence of calcification or deposits Perform decalcification on the machine.
If necessary, dismantle and clean the machine.
Consider using methods to soften the operating Liquid
Incorrect measuring devices display
Verify the functionality of the measuring devices and perform
calibration if necessary
Excessive discharge pressure
Inspect the system and identify the cause of high pressure
High internal clearance losses
Rectify the impeller gap by checking and adjusting it.
If the gap is too large, consider reducing the length of the housing
by dismantling and modifying it
Low inlet pressure
Verify the system and adjust the feeding capacity, such as reducing
the rotation speed or installing a bypass
Internal leaks
Dismantle the machine and inspect the sealing surfaces.
Look for resistance, substitute affected parts if there is corrosion
Defective valves on the discharge side
Replace the faulty valves with new ones
Leaky inlet flange
Examine the seal on the inlet flange and the seal on the inlet-side
inspection cover, replacing them if required
Leaky stuffing box/mechanical seal
Readjust the packing gland assembly.
Check the condition of the stuffing box packing/mechanical seal
and replace them if needed
Insufficient seal liquid flow The volumetric flow of the operating liquid should be increased.
Raise the supply pressure or adjust the volumetric flow of the
operating Liquid