Rotary Compression Technologies LeROI HG10 Assembly instructions

ISO 9001-2000
Installation – Operations
Maintenance and Service Guide
LeROI Gas Compressors
By Rotary Compression Technologies, Inc.
Rotary Screw Compressor
Models:
HG10
HGF10
HG12
HGF12
HGS17
HGSF17
HG17
HG24
LG30
LGL30
RCT-INST001 Rev 6 -8/08
ECN 48316

ROTARY COMPRESSION TECHNOLOGIES, INC.
THANKS YOU FOR PURCHASING LEROI GAS
COMPRESSORS, MODULES AND PARTS

Table of Contents
Safety Information and Warnings________ _________________1
Protecting Your Compressor Before Service_________________2
Identifying Your Compressor_____________________________3
Understanding Your Compressor_________________________4
The Compressor System______________________________5-6
Oil Flow and Orifice Sizing____________________________7-10
Variable Vi Adjustment______________________________11-13
Versatrol (Capacity Control)__________________________14-15
Oil and Related Items_________________________________16
Installation________________________________________17-18
Installation – Component Location________________________19
Operation and Preventive Maintenance____________________20
Service Procedures - Components_____________________21-29
Rebuild Kits_________________________________________30
Website____________________________________________31
Contact List_________________________________________32
Service Diagnosis____________________________________34
Warranty___________________________________________35

1
LeROI gas compressors are designed with safety in mind. However, there is no substitute
for safe operating procedures. Throughout this manual, there will be additional “Notes”,
“Cautions” and “Warnings” intended to protect the operator and the equipment. These
additions are not all inclusive. Extreme care must be exercised when operating or servicing
this equipment.
The operator and or serviceperson should:
•Be knowledgeable of one’s equipment.
•Develop safe work habits.
•Never operate a unit without guards and shields in place.
•Never operate a unit that is not properly electrically grounded.
•Never service a unit with the pressure in the receiver-oil reservoir unless
following specific operation manual instructions.
•Never service a unit without disconnecting and locking out the electrical
power supply unless following specific operation manual instructions.
•Take all necessary precautions, when adjusting controls, etc., to prevent
electrical shock.
•Take all necessary precautions when working with flammable gases to prevent
fire or explosion.
Safety Information and Warnings
A Careful Operator is the Best Insurance
A
gainst an
Accident

2
THIS COMPRESSOR IS SHIPPED WITHOUT OIL. ALTHOUGH
RESIDUAL OIL FROM THE FACTORY TEST IS SUFFICIENT TO PREVENT
RUST DURING SHIPPING, IT DOES NOT PROVIDE ADEQUATE
PROTECTION FOR STORAGE.
IF THE COMPRESSOR WILL NOT ENTER SERVICE WITHIN ONE WEEK OF BEING
RECEIVED, COMPRESSOR OIL MUST BE ADDED THROUGH THE GAS INLET SO THAT
ITS LEVEL IS AT LEAST AS HIGH AS THE BOTTOM OF THE INLET CAVITY. ALLOW A
FEW MINUTES FOR THE OIL TO FILL INTERNAL CLEARANCES THEN ADD TO BRING
LEVEL BACK UP. REINSTALL THE INLET COVER PLATE AND BOLT IT DOWN
SECURELY. THE DRIVE SHAFT MUST BE ROTATED ½ TURN MONTHLY TO INSURE
THAT ALL MOVING PARTS HAVE AN OIL COATING.
Protecting Your Compressor Before Service

3
LeROI gas compressors have a nameplate that provides valuable information
on your compressor. This information is needed for ordering parts and
conversion kits, as well as for accessing warranty information and
understanding the design of the compressor. Below is a Model Designation
chart to help you identify your
compressor.
Identifying Your Compressor

4
Your compressor is either a LG (Low Pressure) or HG (High Pressure) single stage,
positive displacement, oil-flooded screw compressor. There are two basic general
configurations; geared (Figure 1) and non-geared (Figure 2).
Figure 1 - geared compressor Figure 2 -Typical non-geared compressor
Oil-flooding provides cooling, lubrication and sealing in the compressor. The oil must be cooled using either water
or air in a heat exchanger that is properly sized for all operating conditions.
Geared units (Figure 1) come standard with integral gearing to increase or decrease the speed internally, allowing
for direct connection with standard drivers. The drive (input) shaft is an integral extension of the male rotor.
Compressors with gears use an independent input shaft, commonly referred to as a jackshaft, mounted on roller
and/or special deep groove ball bearings. The gear mounted on the jackshaft drives the gear mounted on the male
rotor and the male rotor meshes with and drives the female rotor.
Figure 3 shows the direction of the rotor rotation and
the gas/oil flow through the compressor. Note that
this flow is between the rotors and the inside diameter
(bore of the cylinder).
The uncompressed gas enters the compressor at the
inlet flange, passes into the front bearing retainer, and
enters the cylinder bore at the front (inlet) end. (Figure
3). As the gas passes a predetermined inlet cut-off
point in the cylinder, compression takes place due to
decreasing rotor to cylinder volume as the rotors turn.
Gas at the desired pressure is discharged at the rear
(discharge) end. Oil is injected into the compressor at
specific locations for cooling.
Understanding Your Compressor
Figure 3 - Oil/Gas Flow-Typical

5
The LeROI gas compressor is one part of the compressor system. The compressor combined with the
driver forms the heart of the system. However, the other vital elements are essential to ensure the heart
of your system continues to operate.
Suction Scrubber (with filtration, if necessary)
This is required to prevent the carry over of liquids into the compressor. Filtration is often necessary, especially in vacuum
installations, to prevent debris (e.g. iron sulfides) from getting into the compressor.
Gas/Oil Separator
The gas/oil separator is a key component of the compressor system. The separator should be designed to handle the
maximum capacity at the lowest discharge pressure and the highest discharge temperature. It is important that the vessel and
coalescing filter are sized properly to insure optimum gas and oil separation. The separator also acts as the oil reservoir (oil
sump), with the oil collecting in the bottom.
Oil Cooler
The oil cooler is an air-cooled or water-cooled heat exchanger that is sized to suit the size (capacity) of the compressor being
cooled. The cooler should be designed to handle the worst operating condition, which is usually based on the lowest suction
pressure and the highest discharge pressure. However, the oil flow plays a critical role in determining the heat rejection of the
oil cooler.
Minimum Pressure Valve
The minimum pressure valve is recommended to maintain a minimum pressure in the gas/oil seperator. It is especially
important to use this device when the possibility exists that the system pressure may not be sufficient to maintain pressure in
the seperator to achieve adequate gas/oil seperation.
Thermal By-Pass Valve
The injection temperature of the oil used to cool, seal, and lubricate the compressor is controlled by the thermal by-pass
valve. As the name implies, this valve allows part or all of the oil flow to by-pass the oil cooler, depending on the temperature
of the oil leaving the compressor. This valve can be controlled thermostatically or with more sophisticated temperature
control valve where more precise control of oil temperature is required.
The Compressor System

6
Oil Filter
It is extremely important that the oil injected into the compressor be as clean as possible. The oil filter should be generously
sized to handle full oil flow, and should have a filter element that will remove particles down to 10 micron. If the compressor
is in an application where continuous operation is important or where the filter will get dirty in a short period of time, it is
recommended that a dual filter arrangement be used.
Instrumentation and Controls
The compressor has operating limitations that must be monitored. Protective devices are required to the protect the
compressor from experiencing a catastrophic failure. These include, but are not limited to high temperature and pressure, as
well as liquid level switches in the suction scrubber where there is a potential for large amounts of liquid in the gas stream.
Figure 4 – Typical Basic Piping Diagram
The Compressor System (Continued)

7
As mentioned previously in this manual, rotary screw compressors require oil lubrication of
the bearings, cylinder and rotors. Bearing lubrication is necessary for long life. Cylinder and
rotor lubrication does three things:
1. Reduces friction between the rotors
2. Provides a seal between the cylinder and rotors to reduce gas slippage.
3. Cools the gas.
In certain applications the pressure differential (discharge-suction) is such that an oil pump is not required.
However, if the application has a lower pressure differential than an oil pump will be required. It is
important for the application to be reviewed especially if the unit will be moved from one site to another
resulting in different conditions.
LeROI gas compressors have an oil injection manifold that distributes oil supplied by the pump or pressure
differential. The orifice creates a restriction. A smaller orifice results in a greater restriction, which forces
more oil to the bearing and less oil to the rotors. The goal is to create a proper balance in the compressor
for reliable operation.
Oil Flow and Orifice Sizing
Figure 5 –
T
ypical Oil Flow Figure
6
– Orifice Installatio
n

8
Pumps are installed at the factory based on packager instructions or specified operating
conditions. Every LeROI compressor is tested at the factory to ensure reliable
operation. After testing, the standard orifice or an orifice specified by the customer is
installed in the unit.
IT IS ALWAYS GOOD PRACTICE TO VERIFY THAT THE PUMP AND ORIFICE
SELCTION ARE CORRECT FOR THE FIELD OPERATING CONDITIONS DURING
COMMISSIONING OF THE COMPRESSOR PACKAGE.
There are several size options for each compressor. In the event that an orifice is needed and one is not
readily available one can easily be created. Simply drilling a hole in a solid plug will provide the orifice. It is
also important to note that you may need to create an orifice in the event your desired size is in between
manufacturer available sizes.
Refer to Figure 7 for temperature and pressure methods and locations.
Gas discharge temperature range: 175-210 oF
(Temperature must be high enough to reduce condensation in separator tank.)
High temperature shut down: 230 oF
(Switch must be located between compressor discharge flange and separator tank inlet.)
WARNING! NEVER EXCEED 230oF DISCHARGE
Oil Flow and Orifice Sizing
Temperature/Viscosity/Pressure

9
For Most Situations:
Temperature rise - From oil injection to gas discharge: 30 – 40o F
For heavy gas streams, a 30-40 °F temperature difference may not be possible
Temperature rise – From oil injection to discharge bearing oil drain: 15 oF
WARNING! NEVER EXCEED 20oF BEARING RISE
Oil pressure difference – gas inlet versus oil injection: 60-100 psi
(When gas discharge pressures are 50 psig or less, it may not be possible
to achieve 60 psig oil pressure. That is acceptable if all other specifications are met.)
Oil viscosity at injection temperature: 13-40 cSt
(Refer to oil supplier data for viscosity at actual injection temperature.)
Temperature/Viscosity/Pressure (Continued)

10
Equipment & Measurement Location
Although other permanent instrumentation is
necessary for monitoring overall package
performance, the following are specifically for the
purpose of evaluating the pump and orifice size.
Table 2 Instruments & Measurement Locations
Instrument Data Location
Infrared (IR)
temperature
gun
a. oil injection
temperature
b. gas discharge
temperature
c. discharge bearing
oil drain temperature
(A) pipe
(B) pipe
(C) tube (goes
down on some
models)
Pressure gage or
transducer 1
d. gas inlet pressure (D) inlet pipe
Pressure gage or
transducer 2
e. oil injection
pressure
(E) injection
manifold
Figure 7 -Temperature / Pressure Measurement Locations
Although probes inserted directly in the gas or oil
stream will give more accurate results, an infrared
(IR) temperature gun is recommended for this
procedure. Since a probe cannot be readily used on
the discharge bearing drain, the IR gun will allow a
better comparison.
For best results when using an IR gun, slowly
moving the IR gun over the item to obtain the
highest temperature. Be careful not to pick up
temperatures from background objects.
Temperature measurements at points A, B, and C should
be made on sections of pipe or tube (not fittings) as
close to the compressor as possible.
Pressures at points D and E should be as close to the
compressor as possible. There is typically an unused
port on the oil injection manifold for E. Point D is
located in the package inlet piping. If pressures are not
taken at these specific locations, they should at least be
located on the compressor side of any major restrictions
such as a filter.
WHEN TO CHANGE A PUMP OR ORIFICE
Field Evaluation of Pump & Oil
Injection Orifice Size
B
A
C
D
E
Larger pump or orifice is
required. Use
performance program to
resize
Is gas disch temp more
than 210oF? Reduce oil injection temp
by changing cooler or
thermostat
Is difference between gas
disch & oil injection temp
less than 30oF?
Smaller pump or orifice is
required. Use performance
program to resize
Is diff between bearing
oil drain & oil injection
temp more than 20oF?
OR Is oil injection
pressure less than 60 PSI
above gas inlet? (see
Note)
Install smaller injection
orifice.
Yes
No
Yes
no
No
No
Is diff between bearing oil
drain & oil injection temp
less than 3°F? OR is oil
injection pressure more
than 100 PSI above inlet
pressure?
Install larger injection
orifice.
Yes
Yes
Note: When gas disch
pressure is below 60 PSI it
may not be possible to
achieve 60 PSI oil pressure,
even with the smallest orifice.
This is acceptable if the
bearing oil drain temp is
within spec.
Is difference between gas
disch & oil injection temp
more than 40oF?
No
Is gas molecular weight
high? Yes OK
No

11
Variable Vi is used to minimize the power required by the compressor. It does not change flow
directly, but can allow an increase in flow through more efficient use of power. Vi is the volume
compression ratio of a compressor: V1 / V2. The internal Vi of the compressor is determined by the size
of the discharge port. A small port causes gas to be released later in the compression cycle resulting in a
higher internal Vi, while a larger port allows the gas to be released earlier in the cycle resulting in a lower
internal Vi. The ideal Vi for an application can be calculated if the inlet and discharge pressures and k
(Cp/Cv) of the gas are known.
The compressor makes the most efficient use of power when the internal Vi equals the ideal Vi. For
example, if the internal Vi is high but the ideal Vi is low, the gas is compressed to a pressure greater than
the external pressure prior to being released. On the other hand, if the internal Vi is low but the ideal Vi
is high, gas momentarily flows backward into the compressor and is re-compressed. Both of these
scenarios result in wasted energy.
The standard discharge housings of the HG17, HG24, LG30, and LGL30 compressors have a 4.4 Vi
port, but are fitted with four valves that can be opened to increase the total size of the discharge port, so
that the following internal Vi’s can be achieved.
Vi = 4.4 (HIGH) All valves closed
Vi = 3.0 (MEDIUM) Two inner valves opened (two outer valves closed)
Vi = 1.9 (LOW) All valves opened
Instructions
THE COMPRESSOR CAN BE VERY HOT!
PROTECT YOUR SKIN WHEN ADJUSTING A RUNNING OR HOT
COMPRESSOR.
DO NOT TIGHTEN VALVES.
Valves are not intended to be closed or opened by tightening. Doing so may
damage the valve and/or compressor rotors. The valve should only be turned until
it “touches” the end of its stroke and then backed off about 1/16 of a turn.
The first item to be performed is to determine the ideal Vi of the application.
There are three ways to do this:
(1) Trial and error – adjust the valves while monitoring horsepower draw.
(2) Use the LeROI Screw Compressor Performance Program by alternatively selecting High,
Medium, and Low Vi on the Compressor tab, and see which results in the lowest horsepower.
(3) Calculate the ideal Vi mathematically (or from a spreadsheet calculator available from
www.leroigas.com):
Vi = (P2/P1)1/k
Variable VI Adjustment

12
P1and P2must be in PSIA, and be at the compressor inlet and discharge flanges. Be sure to
account for package pressure drops, which decrease the inlet pressure and increase the
discharge pressure at the compressor flanges. As a quick reference, for a typical natural gas
with k = 1.26, the pressure ratios that correspond to available internal Vi’s are:
Vi P2 / P1
4.4 6.5
3.0 4.0
1.9 2.2
Since there are three available internal Vi settings, each must cover a range of ideal application
Vi’s:
Ideal Vi Select Internal Vi
Greater than 3.5 HIGH (All valves closed)
Greater than 2.5, but not greater
than 3.5
MEDIUM (Inner valves open, Outer
valves closed)
Less than or equal to 2.5 LOW (All valves opened)
After Determining the appropriate Vi ratio perform the following steps to adjust the internal
Vi ratio:
Figure 8:
Compressor discharge end showing four
closed Vi valves fitted with special locknut-
thread protectors.
Compressor models may also have an oil
pump mounted above the two valves on the
left.
Figure 9:
Remove locknuts with wrench before
making adjustments.
It is not necessary to remove the outer
locknuts if only the inner valves are being
adjusted.
The model represented in the figure has a
pump and is part of a package.

13
Figure 10: For MEDIUM Vi, turn the inner
valves counterclockwise until they are fully
out.
DO NOT FORCE THE VALVES.
Once they “touch” the end of their stroke
reverse them by 1/16 of a turn. This also
applies when closing valves.
Figure 11: For LOW Vi, in addition to
turning the valves for MEDIUM, turn the
outer valves counterclockwise until they are
fully out.
DO NOT FORCE THE VALVES.
Once they “touch” the end of their stroke
reverse them by 1/16 of a turn. This also
applies when closing valves.
Figure 12: Reinstall and tighten locknuts just
snugly while holding valves so they do not
turn. The valve positions in this figure are
low Vi. Note that all of the valves are out.
PERIODICALLY LUBRICATE THE
VALVE STEM THREADS WITH
GREASE TO PREVENT RUST AND
ALLOW FOR FUTURE
ADJUSTMENT.
Figure 13: The valves in this figure are in a
MEDIUM Vi position (inner valves out,
outer valves in). It is not possible to hold the
outer valve while tightening the locknut –
just tighten the locknut lightly to prevent
jamming the valve.

14
Versatrol capacity control is used to regulate compressor flow and reduce power requirements.
Versatrol consists of a set of pressure actuated valve assemblies mounted on the side of the compressor.
When opened, these valves allow gas to leave the compression cycle and return to the compressor inlet
prior to compression and delivery, thus reducing flow and horsepower. A valve is closed by applying
actuating pressure and opened by releasing actuating pressure. This can be used to ramp up the
compressor during start up. Start the compressor with all the ports open then close them.
The by-pass valve assemblies are sometimes referred to as unloaders or pockets.
Versatrol is available on the HG12 and larger models. Due to the small cylinder size, the HG12 has two
valves and an external by-pass (Figure 14). All larger models have four valves with an internal by-pass
(Figures 15 and 16).
Depending on actual operating
conditions, Versatrol can reduce
flow by approximately 50% and
power by 25%. Versatrol can be
operated in steps or stepless.
Step Control - each valve is fully
opened of closed. For each valve
opened in sequence, capacity and
power will be reduced by
approximately 13% and 6%
respectively.
Stepless Control - each valve is
positioned anywhere between fully
opened and fully closed, thus
throttling the by-pass and allowing
infinitely variable flow control.
Stepless control is achieved
through the use of electronic
controls, which monitors flow and
power, and adjusts valve position.
LeROI-RCT does not supply
control systems, but they are
commercially available.
Versatrol Capacity Contro
l
Figure 14 -
HG12 showing
one of two
Versatrol pockets.
Second identical
pocket is on the
opposite side
Figure 15 –
HG17 showing
four Versatrol
pockets. HG24
arrangement is
the same
(Pockets 2 and 4
are under the
compressor)
Figure 16 –
LG30 showing
four Versatrol
pockets. (Pockets
on HG17 and
HG 24 are on the
other side)

15
Actuation:
The Versatrol valves can be operated with pressurized air, gas or lubricating fluid depending on
whether it is step or stepless control. The actuation pressure should be the same or nearly the same
as the compressor discharge pressure. The valves should be opened in the 1-2-3-4 sequence and
closed in the 4-3-2-1 sequence, except the HG12. The HG12 can be opened or closed in any
sequence.
Oil may be used for either step or stepless control. Oil taken from the gas/ oil separator or after the
oil pump should have adequate pressure to allow Versatrol actuation. Oil should always be filtered
prior to entering the control system.
Air or gas can be used for step control systems only. Air and gas are compressible and will not allow
accurate or quick control responses. Air can be used for stepless control systems without a problem.
As mentioned previously, the valve is unloaded or opened by reducing the control pressure. When
the control pressure is reduced the higher pressure inside of the compressor opens the valve.
Therefore, it is important for the actuation pressure during the unloading stage to be lower than the
cylinder pressure. To ensure this occurs, the Versatrol valve assembly should be vented to the
cylinder inlet if actuated by gas or oil. If the air is used in the control system then it will have to be
vented to the atmosphere.
NEVER UNDER ANY
CIRCUMSTANCES VENT GAS OR
OIL TO THE ATMOSPHERE
An oversight that occasionally occurs is the testing of a compressor on air with a
vacuum inlet. If the Versatrol valve is vented to atmospheric pressure, the valve
frequently does not open because the pressure in the cylinder is less than
atmospheric pressure.
Plumbing:
Steel or stainless steel tubing and fittings should be used. Copper tubing is not recommended.
Copper and gas can react and reduce the reliability of your system.
Tubing runs should not be any longer than necessary in order to avoid reduced response times
between controls and the Versatrol valves. Tubing should be 3/8”. Tubing size increases in
importance in cold environments or when tubing runs exceed 4 feet.
Control Valve Selection:
Since actuating pressure is applied and released through the same port in the Versatrol assembly, it is
necessary to use a valve that can be turned between the pressure source and a vent (cylinder for oil
and gas, atmosphere for air). Generally, a three or a four-way valve is required. Three-way valves are
a good choice for manually operated Versatrol. Four-way valves are best for automatic, stepless
control systems.
Versatrol Capacity Control Continued
NEVER UNDER ANY
CICUMSTANCES VENT AIR
INTO A GAS COMPRESSO
R

16
The lubrication system is vital for reliable operation of LeROI gas compressors. Following these guidelines
about oil and related items will ensure years of reliable service.
Start-Up: Prior to start-up the compressor should be pre-lubed.
Oil Filter: Check after first 100 hours. Change once a month if continuously operated or every 1000
hours otherwise. Filter must be changed with every oil change.
At the minimum a differential pressure is recommended for the oil filter. A differential gauge
with an alarm is advised.
Viscosity: The packager/user is responsible for selecting oil that is compatible with the gas, and can
maintain minimum viscosity at the operating conditions. The recommended viscosity is 15
centistokes regardless of the operating conditions. The minimum viscosity is 13 centistokes
regardless of the operating conditions.
Oil viscosity greater than 15 centistokes can affect performance, especially horsepower.
Analysis: Oil should be analyzed on a regular basis. Oil should be checked once a week for the first
month, with at least two of those samples being analyzed. If the first month of samples is
okay then the analysis can be reduced to once a month. Increases in water content and metals
should be watched closely. All reputable oil suppliers and manufacturers will analyze oil
samples at no charge.
Recirculation: It is important that the oil recirculates at least two times per minute, especially with heavier
hydrocarbon and water saturated gases. This keeps the oil temperature higher, thereby
reducing the possibility of hydrocarbons condensing and affecting the viscosity of the oil, or
having water condense and cause lubrication problems.
Strainer: When there is an oil pump, it is recommended that a Y-strainer be installed between the
separator and the suction to the pump
It is recommended that a Y-strainer be installed downstream of where the oil leaves the
discharge bearing retainer, and where it is injected in the casing. This will reduce the
possibility of a catastrophic failure if a bearing fails on the discharge end.
Coalescing: The coalescing element in the gas oil separator should be monitored with a differential
pressure gauge. This element should be changed as required. It should be checked at least
once a year. It is important that the filter element have enough surface area to remove oil
from the gas stream.
Gas Filtration: Gas filtration is recommended. Particulate in the gas stream can contaminate the oil and
cause premature failure.
Temperature: Oil temperature in and out of the rear-bearing retainer should be checked regularly. If
differential is greater than 30°F, there may not be sufficient lubrication for that are. This
could also be an indication of worn bearings.
Oil and Related Items

17
The compressor and prime mover must be mounted on a rigid frame so that the drive, piping, etc. are
not subject to strain and/or misalignment. Mounting holes are provided to securely attach the
compressor.
The mounting surface must be a smooth, level surface that will support the weight of the compressor
and handle the associated vibration. Shims must be installed between the frame and the mounting
surface to eliminate strain on the frame.
Adequate airflow for cooling must be provided. Uncontrolled recirculation (from unit to other source)
of hot air must be prevented. Refer to figure 17 for a typical installation.
Installation
Figure 17 –
T
ypical
I
nstal
l
a
t
io
n