IWAKI PUMPS MDM Series User manual

IWAKI Magnetic Drive Pump
MDM Series (Asia Edition: English)
Instruction Manual
Read this manual before use of product

Thank you for selecting IWAKI Magnetic Drive Pump MDM Series. This instruction man-
ual, which is divided into five sections, namely "Safety", "Outline of Product", "Installation",
"Operation" and "Maintenance", deals with the correct handling and operation procedures
for the pump. To make maximum use of the pump and to ensure safe and long time opera-
tion of the pump, please read this manual thoroughly and carefully prior to operating the
pump.
Contents
SAFETY SECTION ...........................................................................................1
OUTLINE OF PRODUCT..................................................................................4
1. Unpacking and inspection ..............................................................................5
2. Model code............................................................................................................6
3. Conditions to be used ......................................................................................7
4. Structure and names of parts.......................................................................8
INSTALLATION ................................................................................................9
5. Installation........................................................................................................... 10
6. Piping .....................................................................................................................11
7. Electrical wiring................................................................................................. 13
8. Protection ............................................................................................................ 13
OPER ATION ................................................................................................... 14
9. Precautions on operation............................................................................. 15
10. Operation (Starting) ........................................................................................ 16
11. Pump stopping ........................................................................ 16
MAINTENANCE ............................................................................................. 17
12. Trouble shooting...................................................................... 18
13. Maintenance & inspection .......................................................20
14. Disassembling & assembling................................................... 21
15. Repair parts list .......................................................................27
16. Mass of pump .........................................................................45

- 1 -
For the Safe and Correct Handling of the Pump
●Before use of the pump, read carefully this "Safety Section" to prevent accidents and to avoid the
damage or loss of other assets.
●Observe and abide by the instructions described in this "Safety Section". These instructions are
very important for protecting pump users or other persons from hazard or from loss of assets.
●Meaning of symbols
Following two symbols describe the extent of hazards and loss which may brought if the instruc-
tions are not observed or if the pump is wrongly used.
Following two symbols describe the content to be observed.
SAFETY SECTION
Warning
Nonobservance or misapplication of the contents of
the "Warning" could lead to a death or heavy injury of
person.
Caution
Nonobservance or misapplication of the contents of the
"Caution" could lead to a injury of person or damage of
assets.
Prohibited action or procedure is indicated. Inside or
near this circle, a concrete activity to be prohibited is
depicted.
Action or procedure which must be performed without
fail is indicated. Inside this circle, a concrete activity to
be performed is depicted.
Export Restrictions
Technical information contained in this instruction manual might be treated as controlled
technology in your countries, due to agreements in international regime for export control.
Please be reminded that export license/permission could be required when this manual is
provided, due to export control regulations of your country.

- 2 -
Safety Section
WARNING
●Magnetfielddanger
The magnet drive pumps contain very strong magnets. The strong magnet field could
adversely affect persons who are assisted by electronic devices such as pacemakers
etc.
●Always turn off power supply prior to maintenance works etc. Pay special attention so
that no other operator turns on by mistake the power supply while someone is working
on the pump. In a noisy or poor visibility environment, display a sign near power sup-
ply switch to notify other person that someone is "WORKING" on the pump. Power
supply mistakenly turned on during maintenance works may lead to personal injury.
Each operator must pay special attention.
●Wearprotectors
When piping is removed or pump is disassembled/assembled, wear protective gear
such as safety goggles and protective gloves etc.
●Liftingpump
When pump is lifted, apply chain or belt to eye bolt and motor to keep the pump &
motor horizontally.
●Noremodeling
Remodeling of pump may result in serious personal injury or damage of the pump. Do
not attempt remodeling pump because it is very dangerous.
Power off
Wear protective
gear
No Remodeling
●Dangerousliquid
When the pump is used to transfer dangerous liquids mentioned as below, the pump
must always be checked and watched so that the liquid can not be leaked. The opera-
tion of pump leaking the liquid may result in personal injury, explosion or fire accident.
● Explosive or flammable liquids
● Corrosive or stimulus toxic liquids
● Liquids harmful to human health

- 3 -
Safety Section
CAUTION
●Attentiontomagneticforce
This pump employs strong magnets. Special attention must be paid not to be injured
by attracting force of magnets. Follow the procedure "Disassembling and Assembling"
when the maintenance works are done.
●Donotrunpumpdry
Do not run pump dry (without liquid). If the pump run dry, heat is generated by rub-
bing, which causes pump damage. If the pump is operated with suction side valve
closed, the pump runs dry.
●Countermeasuresforstaticelectricity
When low electric conductivity liquid such as ultra-pure water and fluor inactive liquid
(e.g. Fluorinert™ are handled, the static electricity may be generated in the pump,
which may cause static discharge and pump break down. Take countermeasures to
avoid and remove the static electricity.
●Qualifiedoperator
The pump must be handled or operated by the person who has enough knowledge
and well acquainted with the pump.
●Forspecifiedapplicationonly
The use of pump in any application other than those clearly specified may result in the
failure or damage of the pump.
Do not run dry
●Disposalofusedpump
Disposal of used or damaged pump must be done in accordance with local laws and
regulations. (Consult a licensed industrial waste products disposing company.)
●Ventilatethesite
When handling the liquid which may generate toxic gas, safety measures such as
ventilation must be taken to prepare for the accidental liquid leakage.
●Countermeasuretoliquidflowingout
Protective measurement must be taken against liquid flowing out caused by damage
of pump or pipe by accident. Also, appropriate measurement must be taken so that
the liquid can not directly flow out on the ground.
●Eliminateairinpumpchamber
Before full operation of pump, run pump to eliminate air from pump chamber.
Above all when pumping liquid which easily generates bubbles (hydrogen perox-
ide, sodium hypochlorite or so), eliminate air every time when pump is operated.
Operation of pump with air remaining in pump chamber may heat rubbing parts of
pump resulting in pump damage.

- 4 -
1. Unpacking and inspection ........................5
2. Model code ..................................................6
3. Conditions to be used ...............................7
4. Structure and names of parts..................8
OUTLINE OF PRODUCT

- 5 -
After unpacking of the pump, check the following
points.
(1) If the product is ordered one.
Check model code, discharge capacity, discharge
pressure, voltage which are written on nameplate
of pump and motor to see if they conform to your
order.
(2) If the product is not damaged or bolts are not loos-
ened during transportation. Tighten especially the
bolts which are holding a rear casing support to the
specific tightening torque subsequent to the first
tightening. Refer to the "13.Disassembling & assem-
bling" for the specific torque value.
(3) If accessories are attached.
Standard accessories:
Bolts for back pull-out M12 × 100: 2pcs
(M10 × 50 : 2pcs for MDM25-1)
Optional accessories if ordered
1. Unpacking and inspection
Eye bolt
Motor nameplate
Foot support
Pump nameplate
Baseplate
Suction port
Discharge port

- 6 -
MDM40 - 150 1 E KK F 075 J - D 2 H
1 2 3 4 5 6 7 8 9 10 11
1 Pump discharge bore Suction Discharge
25: 40 × 25
40: 50 × 40
50: 65 × 50
65: 80 × 65
2 Nominal impeller diameter: 100 - 225 (mm)
3 Impeller range: 1: Low head impeller type 2: High head impeller type (Available for MDM25 and MDM40)
3: High head impeller type (Available for MDM25 only)
4 Main material: E: CFRETFE P: PFA N: PFA (MDM40-1 only)
Note) Pumps with the "P" and "N" codes have PFA main materials, but then casing design is different from each other.
See the section 15. Spare parts list for detail.
5 Bearing/spindle material: KK:SiC/SiC CF:High density carbon/High purity ceramic
6 Type of motor to be mounted: F : Flange mounted motor type
7 Motor output: 004 : 0.4 kW, 007 : 0.75 kW, 015 : 1.5 kW, 022 : 2.2 kW,
037 : 3.7 kW, 055 : 5.5 kW, 075 : 7.5 kW, 110 : 11 kW, 150 : 15 kW, (185 : 18.5 kW)
8 Standard for connection flange/motor
J : JIS pump flange + JIS motor I : ISO pump flange + IEC motor A : ANSI pump flange + JIS motor
9 Drain/special version
2. Model code
Note: For the pumps with the main material code of "P", an air vent is always equipped for "with drain" type.
10 Motor pole : 2 : 2 pole motor
4 : 4 pole motor
11 High temperature type
No code : Standard
H : High temperature type
(Available for MDM25-3 and MDM40-2)
Note) In this manual, model code is simplified by using pump discharge bore code (1) and impeller range code (3). For
example, when you see MDM25-1, MDM25-2, MDM25-3, MDM40-2, the figures 25 or 40 are pump discharge
bore and 1, 2 or 3 are impeller range.
Baseplate Standard or Special version
A
With baseplate
Standard
S
D
X Special version
B
Without baseplate
Standard
Y
E
Z
Drain
Without drain Special version
With drain Standard
Without drain Special version
With drain Standard
Special version

- 7 -
1. Maximum operating pressure
Maximum operating pressure of the pump is 1 MPa (1.6 MPa for MDM25-3 and MDM40-2). Pay attention so that
the pump discharge pressure does not exceed this figure.
2. Slurry containing liquid
Basically slurry containing liquid can not be handled but SiC bearing type (KK type) can handle it in the following
conditions:
• Slurry concentration up to 5 wt%
• Slurry hardness up to 80 Hs
• Slurry size up to 50 µm
3. Performance change caused by specific gravity and viscosity of liquid
When specific gravity and viscosity are larger than water, shaft power, discharge capacity and discharge head will
change depending on specific gravity and viscosity of pumped liquid. The pump was made and shipped according
to the information given to IWAKI. If the liquid condition is changed, ask and confirm IWAKI to use the pump
without problem.
4. Influence by liquid temperature
The chemical liquid changes its viscosity, vapor pressure and corrosivity according to the temperature change. Pay
attention to the change of liquid characteristics.
3. Conditions to be used
Note 1) The code "E", "P" and "N" represents main materials.
2) For temperature range of each chemical liquid, refer to Chemical Resistant Table on booklet "Technical
Information on MDM Series".
3) For liquid temperature below zero deg. C and above 120 deg. C, please contact IWAKI because detailed
operating condition must be considered for these temperature ranges.
Ambient temperature range: 0 - 40 deg. C
Ambient humidity range: 35 - 85% RH
Liquid temperature range
-20 0 100 150
Pumped liquid
temperature (deg. C)
E (all models)
P (MDM25-1/ 25-2/ 40-1/ 50-1/ 65-1)
P (MDM25-3/ 40-2)
12080
N (MDM40-1)

- 8 -
4. Structure and names of parts
Note (1): Q'ty in parenthesis (6) is for MDM25-1 and (10) is for MDM25-3 & MDM40-2.
(2): For high temperature type "H" of MDM25-3 & MDM40-2.
(3): For pumps with the main material codes of "E" (all models), "P" (MDM25-1) and "N" (MDM40-1).
NO. Parts name Q'ty NO. Parts name Q'ty
100.1 Front casing 1554.1 Spring washer 2
100.2 Cover 1554.2 Spring washer 2
122.1 Drain plate 1554.3 Spring washer 2
122.2 Air vent plate 1554.4 Spring washer 8 (6) or (10) Note (1)
158 Rear casing 1554.5 Spring washer 4
159 Rear casing cover 1554.6 Spring washer 4
159.1 Reinforce pipe Note (2) 1554.7 Spring washer 2
161 Rear casing support 1801 Motor 1
210 Spindle 1858 Drive magnet unit 1
230 Impeller 1859 Magnet capsule unit 1
310 Bearing 1890 Base plate 1
314.1 Liner ling 1900 Eye bolt 1
314.2 Mouth ring 1901.1 Hex. head bolt 2
314.3 Rear thrust 1901.2 Hex. head bolt 2
314.4 Rear ring 1901.3 Hex. head bolt 2
330 Bracket 1901.4 Hex. head bolt 8 (6) or (10) Note (1)
400.1 Gasket 1901.5 Hex. head bolt 4
400.2 Drain gasket 1901.6 Hex. head bolt 4
400.3 Air vent gasket 1901.7 Hex. head bolt 2
500.1 Plain washer 2903.1 Hex. head bolt Note (3) 5
500.2 Plain washer 2908.1 Hex. socket head bolt 2
500.3 Plain washer 2942 Impeller pin 2
500.3
554.3
901.3
400.3
122.2
901.1
554.1
400.2
500.1
122.1
500.2
554.2
554.4
901.7
554.5 554.6
901.2
903.1
901.4
890
554.7
901.6
330159.1
908.1
314.3
314.4
858
161
859
310
210
801
900
159158
901.5
400.1
942
314.1
314.2
100.1100.2 230

- 9 -
5. Installation..................................................10
6. Piping ..........................................................11
7. Electrical wiring.........................................13
8. Protection ...................................................13
INSTALLATION

- 10 -
5. Installation
Example of recommended piping
1 Discharge pipe
2 Discharge valve
3 Check valve
4 Pressure gauge
5 Motor
6 Pump
7 Flexible joint
8 Vacuum gauge
9 Suction pipe
10 Suction valve
11 Gate valve
12 Air vent piping
13 Pipe support
1. Installed position
• Install and fix the pump on the foundation which is not affected by vibration generated by other machines.
• Keep enough space around the pump for the back pull-out of motor, assembly and disassembly of the pump.
• Foundation area must be larger than pump base plate.
2. Location
• Install the pump as close to the tank as possible and at lower position than the tank (flooded suction).
• If the pump is installed at the location that the pump suction port comes higher position than the liquid level
of tank (suction lift style), install the priming piping and foot valve at the end.
3. Foundation
• Refer to illustration below.
1
2
3
11
10
13
10
12
11
6
5
97
4
87
12
Within
1m
Concrete foundation
Foundation bolt
Baseplate liner

- 11 -
6. Piping
1. Tightening of pipe flange
Table below shows the bolt size and tightening torque for the connection of pipe flange to pump flange. Tightening
torque is the figure when metallic flange and rubber gasket are used.
2. Pipe load and moment
Pipe load and moment put on the pump should not exceed the figures shown below.
Bolt size
M16
Tightening torque
78.4 N · m
Z
X
Y
X
Z
Y
Allowable pipe load on pump flange
Allowable moment on pump flange
Direction of load Suction flange
Fx
Fy (Pression/Tension) 0.58
Fz 0.89 0.71
Load kN
Discharge flange
MDM25, 40, 50
0.71 0.89
0.58
MDM25, 40, 50 MDM65 MDM65
1.07 1.33
0.89/0.44 1.33/0.67 0.89
1.07
Direction of load Suction flange
Mx
My 0.35
Mz 0.47 0.23
Moment kN · m
Discharge flange
MDM25, 40, 50
0.46 0.46
0.23
MDM25, 40, 50 MDM65 MDM65
0.95 0.95
0.35 0.72 0.72
0.47

- 12 -
3. Suction piping
(1) Flooded suction
Flooded suction is recommended.
(2) Pipe diameter
Pipe diameter should be larger than pump inlet bore.
(3) Shortest piping
Employ less bends and shortest piping length.
(4) Straight piping
Employ straight pipe just before pump inlet port.
Pump inlet bore 50A or smaller : Straight pipe of 500 mm or longer
Pump inlet bore 65A or larger : Straight pipe of 8 times as larger than inlet port
For the easy pump dismantling and maintenance, install a removable short length pipe of 300mm or so in straight
piping.
(5) Air pocket in piping
Do not allow any projection in piping where air may be trapped along the suction pipe.
Suction pipe should have an ascending gradient of 1/100 toward the pump.
(6) Different diameter of pipes
If diameter of pump suction port is different from that of suction pipe, use the eccentric reducer pipe. Connect
the eccentric reducer pipe so that upper side is level. Residual air may not go out if it is mounted in reverse.
(7) Gate valve in suction side
In case of flooded suction, install gate valve in suction piping. It is needed when the pump is disassembled and
inspected.
(8) Piping for flushing
Install pump flushing piping in case that the dangerous liquid will be handled.
(9) End of suction piping
The end of suction pipe always should be located 500 mm or more below the liquid level. Take care so that air
can not be sucked in suction piping.
(10) In case of suction lift piping
• The end of suction piping should be 1 to 1.5 times of pipe diameter or more away from the bottom of suction tank.
• Install foot valve or check valve in suction piping.
(11) Pipe support
Install the pipe support so that the weight of pipe can not be directly loaded to the pump.
(12) Pipe connection
Pipes must be connected securely so that the air can not be sucked in. If the sealing is not perfect, air is sucked
in, which causes pump damage.
4. Discharge piping
(1) Pipe diameter
In case the discharge piping is long, the specified performance may not be obtained because of unexpected pipe
resistance if the pipe diameter is the same as pump bore. Calculate the pipe resistance in advance to decide proper
diameter of pipe.
(2) Position of the first valve
Take 1m or so distance between pump and the valve located the nearest to pump and install air eliminating piping
at the place close to the nearest valve to the pump so that air can not remain in pump. Refer to "Example of recom-
mended piping" on page 10.

- 13 -
(3) Gate valve
Install the gate valve in discharge piping to adjust flow rate and to protect motor from over loading. If the check
valve is also installed, recommended arrangement is : Pump → Check valve → Gate valve
(4) Pressure gauge
Install a pressure gauge in discharge piping to check the operating conditions such as discharge head etc.
(5) Check valve
Check valve must be installed in the following cases.
• Discharge piping is longer than 15 to 20 meters.
• Actual head exceeds 15 meters.
• Height difference between liquid level and discharge pipe end exceeds 9 meters.
• When two pumps are used in parallel.
(6) Air vent
If horizontal discharge piping is longer than 15 to 20 meters, install air vent on the way.
(7) Drain
If the liquid must be drained to protect from freezing, install the drain valve.
(8) Pipe support
Install the pipe support so that the pipe weight can not be loaded to pump.
(9) Priming piping
Install piping for priming in case of suction lift.
7. Electrical wiring
Electrical works or wiring must be carried out by qualified and authorized person according to local law or regulation.
• Use the electromagnetic switch which conforms to motor specifications such as voltage and capacity etc.
• If pump is installed outdoor, wiring must be done so that water can not get into switch.
• Electromagnetic switch and push-button switch must securely installed apart from the pump.
• Star-delta starter, inverter or soft starter is recommended to start the motor of 5.5 kW or more power which drives the pump.
* See the instruction manual of the motor manufacturer for the handling of the motor.
It is recommended to install the following monitoring devices to protect the pump.
1. Current sensor/Power sensor The sensors monitor the motor load and stop the pump on the detection of load change.
2. Pressure sensor The sensor monitors the starting pressure and stops the pump on the detection of
pressure change.
3. Flow sensor The sensor monitors the discharge flow and stops the pump on the detection of
flow change.
4. Level sensor The sensor monitors the liquid level and stops the pump when it falls below the
specified level.
It is recommended to install two or more monitoring devices. The more monitoring devices are installed, the more
possibility of protecting the pump.
The DR series dry running protector (electric current sensing type) is also available as an option. Contact us for detail.
8. Protection

- 14 -
9. Precautions on operation........................15
10. Operation (Starting) .................................16
11. Pump stopping ..........................................16
OPERATION

- 15 -
9. Precautions on operation
CAUTION
●Never operate pump dry or with suction side valve closed.
●Dry running possible model (CF type of carbon bearing) can run dry (completely no liquid in pump)
continuously one hour max. However rubbing parts are worn in a short time which will result in pump
damage in the worst case if pump runs dry continuously exceeding one hour or if it runs dry repeatedly
although it is short time.
●After the pump ran dry, leave the pump one hour or more for cooling down to start it once again. If the
liquid flows into the pump just after the pump ran dry, ceramic parts are cracked due to heat shock.
●Check the direction of rotation of pump. Clockwise seen from motor fan is correct direction. If operated in
reverse, pump may be damaged.
●Stop the pump within one minute if it is operated in cavitation.
●Do not run pump with air sucking in.
●If magnet coupling is disconnected, pump can not transfer liquid. Stop pump within a minute and settle
the cause of disconnection before pump is started again.
●Intermittent operation
Frequent repetition of stop/start is not recommended. Stop/start repetition must be limited to six times an
hour. Frequent stop/run more than six times an hour may cause accelerated damage of parts and low-
ered durability.
●Temperature change at starting, stopping and operating of pump must be within 80 deg. C.
●Fully close the discharge valve when pump is started to avoid water hammer.
●If the pump is operated with discharge valve closed for a long time, the liquid temperature inside the
pump rises, which may cause pump damage. Do not run the pump for more than one minute with dis-
charge valve closed.
●If power is interrupted while pump is running, switch off pump and close discharge valve.
●Pay attention so that discharge pressure can not exceed pump allowable pressure of 1 MPa.
Check that there is no looseness on each bolt before operating pump. Tighten especially the bolts which
are holding rear casing support to the specific tightening torque subsequent to the first tightening. Refer
to the [13.Disassembling&assembling] for the specific torque value.
●Observe the allowable minimum flow rate. If the pump is operated below the allowable minimum flow
rate, bearing or rubbing parts may be seized due to lack of lubrication and cooling.
Allowable min. flow rate MDM25 : 20 /min.
MDM40, 50, 65 : 50 /min.
●When high temperature liquid is transferred, pump surface becomes very hot. Take protective measure
against burn.
Liquid temp. Max. pump surface temp. (Amb. temp. 40 deg.C)
80 deg. C 70 deg. C
100 deg. C 90 deg. C
120 deg. C 110 deg. C
150 deg. C 135 deg. C
●Pump noise
85 dB for MDM25-1, 25-2, 40-1, 50-1
95 dB for MDM25-3, 40-2, 65-1

- 16 -
10. Operation (Starting)
1. Fully close discharge valve and fully open suction valve.
2. Fill liquid into pump
•In case of flooded suction, confirm if suction valve is fully opened.
•In case of suction lift, prime to fill liquid into suction piping.
3. Check rotating direction of motor.
•Start motor momentarily (within a second) to check direction. Direction is shown on "arrow" mark on pump.
(Clockwise seen from motor fan side)
•Also check if motor fan smoothly stops when switched off. If it does not stop smoothly, pump rotating parts
may be locked. Check the rotating parts.
4. Air vent operation
•Before pump operation, vent the air in the pump.
•Fully open the valve in air vent piping and repeat one second running for three to five times.
•After the air vent running, fully close the discharge valve.
Note: In case air vent piping is not equipped, open the discharge valve to repeat momentary run several
times.
5. Starting pump
• Start pump with discharge valve fully closed. (Maximum one minute)
• Confirm that discharge pressure rises to shut-down pressure.
• Gradually open discharge valve to get specified pressure (capacity).
Note: Pay attention to over-load caused by excessively opened valve.
Keep minimum allowable capacity to avoid seizure of bearing or rubbing parts.
11. Pump stopping
1. Slowly close the discharge valve
Quick closing of valve may cause water hammer and pump damage.
2. Switch off and stop the pump
Confirm if pump stops smoothly. If pump stops suddenly and not smoothly, inspection is needed.
3. When the pump is stopped for a long period, anti freezing measure must be taken so that the liquid can not be frozen
in the pump or piping.
2P
MDM25 20 /min
4P
10 /min
MDM40, 50, 65 50 /min 20 /min

- 17 -
12. Troubleshooting ........................................18
13. Maintenance & inspection ..................... 20
14. Disassembling & assembling.................21
15. Repair parts list.........................................27
16. Mass of pump........................................... 45
Maintenance

- 18 -
12. Troubleshooting
Troubles
Liquid
can not be
sucked
• Lack of priming
liquid
• Dry running
• Foot valve is cl-
ogged by foreign
matters.
• Stop pump and reple-
nish pump with liquid
to re-start.
Primed liquid drops
quickly
• Clean foot valve
• Check if foreign matters
are not adhered to valve
seat.
When disch. valve
closed
After starting, pres-
sure drops as soon
as discharge valve is
opened.
• Air is sucked from
suction pipe or gas-
ket.
• Check if connected
flanges are completely
sealed.
• Check if liquid level of
tank is not excessively
lowered.
• Disconnected ma-
gnet coupling
• Check amperage to see
if motor is not overload-
ed.
• Check if foreign matters
do not lock impeller or
magnet capsule
• Check if voltage is nor-
mal.
Press. gauge shows
low pressure
• Low pump speed
• Reverse rotation
• Check wiring or motor.
• Interchange wiring con-
nection.
Discharge
capacity is
small.
Pressure gauge &
vacuum gauge indi-
cates normal figure.
• Strainer is clog-
ged by foreign
matters.
• Remove foreign mat-
ters.
• Air pocket in suc-
tion piping
• Check and remedy suc-
tion piping.
• Foreign matters
are clogged at
impeller inlet.
• Remove foreign mat-
ters.
• Air is sucked in
from suction pipe
or gasket.
• Check connection part
of pipes and retighten it.
• Foreign matters
clog at discharge
side.
• Remove foreign mat-
ters.
• Remove foreign matters
or scales in piping.
Symptom on pump
Cause Check & countermeasures
When disch. valve
opened
Press. gauge & vac-
uum gauge indicate
zero.
Pressure gauge vi-
brates and drops to
zero.
Vacuum gauge indi-
cates high figure.
Vacuum gauge
indicates very high
figure.
Pressure gauge &
vacuum gauge vi-
brate.
Vacuum gauge indi-
cates hign but pres-
sure gauge indicates
normal.
• There are resis-
tance such as air
pocket etc. in suc-
tion piping.
• Check if there is not
protruded section in
suction piping.