Rainman WM Series User manual

WM and WMR Series
High Pressure Pump Service
Rainman Technology Pty Ltd
#17 / 10-18 Orchard Road
Brookvale, NSW 2100
Australia
www.rainmandesal.com
[email protected]
[phone]
Version 1.1

Table of Contents
Pump Description 1
Routine Pump Maintenance 2
Oil Change 2
Preventing Cavitation 2
Replacing the Valves 3
Overview 3
Procedure 4
Replacing the Packings 6
Overview 6
Procedure 7
Setting Relief Valve 12
Troubleshooting 14
Maintenance Log 15

High Pressure Pump Servicing Instructions – Page 1
Pump Description
The high pressure pump is the heart of your Rainman watermaker. It creates the high pressure required for
the reverse osmosis membranes to extract the fresh water from seawater. We use the best quality piston
pump from General Pump, an American subsidiary of Interpump Group in Italy. Although it is a very simple
and highly reliable pump, basic maintenance is required to maximise its performance and life span. Many
customers may never need to read beyond the Routine Pump Maintenance section of this manual. However,
the rest of this manual is included to assist those that may need to perform greater levels of maintenance on
more heavily used systems.
Depending on which Rainman watermaker model you own, there will be one of two different high pressure
pumps in your system. If you have the older Mk1 electric (either AC or 12VDC) manufactured through
January 2019, or any petrol (gasoline) model, your system will have a General Pump WM Series pump. If you
own an electric (AC or 12VDC) Mk2 system, manufactured after February 2019, your system will have a
General Pump WMR Series pump.
The internals of both pumps are almost identical with only minor changes that are mostly in the manifold
(stainless steel section of the pump). The photos and exploded diagrams in this document are for the WMR,
but are almost the same for the WM pumps. All procedures described in this document apply equally to the
WM and WMR pumps.
General Pump WM Series (left) and WMR Series (right) high pressure pumps

High Pressure Pump Servicing Instructions – Page 2
Exploded view of WMR series pump showing pistons and manifold
Routine Pump Maintenance
Very little routine maintenance is required on your General Pump high pressure pump. Required
maintenance is in your operations manual, but is also included here for completeness of this document.
Oil Change
When replacing the oil in the pump, use SAE-30 weight oil. General Pump generally recommends an oil
change after the first 50 hours, then after each 300 hours of use thereafter. These pumps are designed for
significantly higher operating pressure and flow rates, so the oil break down is slower than normal operation
for this design. As such, it is not critical to maintain high discipline on this oil change schedule.
The method to change oil in your pump is outlined in the watermaker operations manual.
Preventing Cavitation
The most important maintenance required to maximise the life of your pump is to prevent pump cavitation.
Symptoms of cavitation include extra noise, high pressure hose vibration, and significant pressure
fluctuation. Causes are anything that restricts flow to the pump. The watermaker operations manual covers
more detail, but the two most frequent causes are not changing the prefilter or lift pump impeller frequently
enough.
Extended cavitation will prematurely wear the packings.

High Pressure Pump Servicing Instructions – Page 3
Replacing the Valves
Overview
Each of the three cylinders in the pump has two spring loaded one way valves. One valve allows water to be
pushed into the cylinder by the lift pump as the piston retracts. The second valve opens as the piston forces
the water under high pressure through the manifold. O-rings are used to seal around the valves.
Only one valve kit (RM01) is necessary to replace all the valves in the pump. The kit includes new O-rings and
valve assemblies.
Exploded view of WMR series manifold, showing valve configuration

High Pressure Pump Servicing Instructions – Page 4
Procedure
1. Using a 22mm spanner or socket, remove the valve cap. Examine threads and O-ring. Replace O-ring
(item 1) if there is any evidence of cuts, abrasions, distortion or wear.
2. Remove valve assembly (item 2) from valve cavity.
3. Remove valve seat O-ring (item 3) from valve cavity.
4. Inspect manifold for wear or damage.
5. Install new O-ring (item 3) in valve seat cavity.

High Pressure Pump Servicing Instructions – Page 5
6. Insert valve assembly (item 2) into valve cap as
shown.
7. Coat the threads of the valve cap with anti-seize
grease (such as Renolit ST-80) and reinstall valve cap.
Torque to 40 Nm (30 Ft-Lbs).

High Pressure Pump Servicing Instructions – Page 6
Replacing the Packings
Overview
The purpose of the packings is to allow the pump to push water through at high pressure while also
preventing it from leaking out of the pump along the pistons. The hard high pressure seals contain the
pressure within the manifold of the pump, but some moisture slides out with the piston on each stroke. The
softer low pressure seals then prevent the water from leaking out of the pump. Normal symptoms of worn
packings is water dripping from the weep holes underneath the pump.
General Pump WMR packing kit

High Pressure Pump Servicing Instructions – Page 7
In the photo to the right are the following seals from top to
bottom:
• Low pressure seal (item 2 in diagram).This is the one
with stainless steel spring visible inside .
• Stainless ring case (item 4 in diagram) with O-ring
(item 3). Ensure O-ring is on the case, and is sitting in
the correct groove as per photo to the right (the one
without holes). If O-rings in the kit came separated
from steel casing put them on before proceeding
• Glyd high pressure seal, (item 5 in diagram).
• Square high pressure seal, (item 6 in diagram).
Procedure
1. Remove head bolts using a 5mm Allen key and slide manifold away from the crankcase. Remove it as
straight as possible so as not to stress the plungers or rods inside the power end of the pump. It is
normal for some packing assemblies to remain on the plungers. It may be necessary to rotate the
crankshaft and/or use pry bars to separate manifold from crankcase.
2. Remove the low pressure seals (item 2) using your
fingers. Take careful note of which way seals were
facing in order to correctly insert the new seal later.

High Pressure Pump Servicing Instructions – Page 8
3. Remove the stainless steel case (item 3 / 4) where low pressure seals (item 2) were installed. Tightness
of stainless casings varies from pump to pump. It may be possible to remove the rings by inserting a
finger and pulling outwards. If more force is necessary, use a 17-18mm diameter object (such as a
blind bearing puller or screwdriver handle) and gently pull them out with a slight rocking motion. Since
they are being replaced, damage to the old packings is inconsequential. Important: take care not to
score or mark the manifold's machined surfaces.
4. Remove high pressure seals (item 5 / 6) using your
finger by gently pulling them upwards. If more force
is necessary, try using plastic or timber tools in order
to avoid damaging machined surfaces of cavity. Take
careful note of the seal’s orientation in order to
correctly insert the new seals later.
5. Thoroughly clean and inspect cavity for unusual wear
or cracks.
6. Press the glyd high pressure seal (item 5) into square
high pressure seal (item 6).

High Pressure Pump Servicing Instructions – Page 9
7. Set the high pressure seal insertion guide (item 8) in
manifold cylinder. Do not grease any portion of the
packing assembly during this step.
8. Gently place assembled glyd rings (items 5 / 6) inside
insertion guide (item 8) so they are resting evenly.
9. Insert pusher tool (item 9), blunt end facing forward
and firmly press down to set glyd rings (items 5 / 6) in
the manifold.

High Pressure Pump Servicing Instructions – Page 10
10. Set low pressure seal guide (item 7) over seal casing
(item 3 / 4) ensuring recess for seal is facing upwards.
11. Gently place low pressure seal (item 2) into the guide (item 7) ensuring the open spring side of the
seal is facing toward the casing and resting evenly.
12. Insert pusher tool (item 9) into collar with narrow end
facing forward. Firmly press down to set seal in casing.

High Pressure Pump Servicing Instructions – Page 11
13. Confirm that the O-ring is in the correct groove on
casing (item 3 / 4). At this point you should not be
able to see the spring in the low pressure seal (item
2) as it should be facing toward the casing itself.
14. Check that spacer rings (item 1) are on each plunger
as per photo. These rings are non-wearing so it is not
required to replace them. Apply a very thin coating of
silicone grease to each plunger.
15. Slide the casings (items 3 / 4). on each plunger using low pressure seal guide (item 7). Ensure the black
low pressure seal (item2) faces towards the power end of the pump, as per photo. Ensure they are
straight to prevent damaging new seals.

High Pressure Pump Servicing Instructions – Page 12
16. Reseat the manifold gently pushing it back into place.
Install it straight with minimum wiggle.
17. Once manifold is properly seated, install head bolts
and begin torque sequence. Tighten to 12 Nm or 8.9
Ft-lbs.
Setting Relief Valve
A relief valve is part of every Rainman watermaker as a safety precaution. It prevents build up of excessive
pressure in the RO system if the control valve is accidentally closed too far. If the system does get over
pressured, the relief valve opens and recirculates water through the pump to ensure no damage or high
pressure leaks occur.
In normal use the relief valve remains closed at all times. If the pressure reaches approximately 62 bar (900
psi) the valve starts to open, returning some water to the intake side of the system. At approximately 69 bar
(1000 psi) it will be completely open, limiting the maximum output pressure of the PSU to approximately 69
bar (1000 psi). All relief valves are set in the Rainman factory during final testing of each system. In the highly
unlikely event that a relief valve needs to be replaced, it will need to be set to the correct opening pressure.
This section describes the procedure for setting the correct opening pressure, using the pressure gauge on
any of the Rainman RO systems. It should be emphasised that it is highly unlikely you will ever need to
replace or adjust the relief valve.
All petrol/gasoline systems and original design, pre-January 2019, Mk1 electric systems utilise the VS100
relief valve, which is separate to the WM series pump itself. On Mk2 electric systems, manufactured after
February 2019, the WMR pump has an integrated relief valve built into the manifold. You will need to
remove the shell to access the relief valve on all cased electric systems. A separate document exists to
remove the shell on Mk1 electric systems.
Petrol/gasoline PSU WM Pump Mk1 Electric PSU WM Pump Mk2 Electric PSU WMR Pump

High Pressure Pump Servicing Instructions – Page 13
Note that the VS100 relief valve is installed upside down on the Mk1 Electric PSU with the WM pump.
Directions here are given as if you are looking at the end hexagonal adjustment cap.
Once you have replaced the relief valve, and before replacing the plastic case of your PSU, reconnect the
particle filter housing so that you can perform the following steps.
1. Loosen the locking nut underneath the large
hexagonal part of the relief valve.
2. Place the pickup hose into a water source and connect
the RO unit as during normal operation.
3. With the pressure control valve on the RO system fully
open (counter-clockwise), run the PSU until only clear
bubble free water comes out brine hose.
4. Turn the pressure control valve clockwise until it is
fully closed whilst watching the pressure on the gauge.
New relief valves from the factory are typically pre-set
to a low pressure, so you should be able to close the
valve fully before the pressure reaches 55 bar (800
psi). If the pressure reaches 55 bar (800 psi) before the
valve is fully clockwise, then the relief valve is already
set too high. In this case, turn the hexagonal part of
the relief valve anti-clockwise three times and go back
to step 3.
5. With the PSU running and the pressure control valve
fully closed (clockwise), turn the adjustment cap on
the relief valve clockwise until the pressure gauge
reaches 55 bar (800 psi).
6. Fully open the pressure control valve on the RO unit
(anticlockwise) and turn off the PSU.
7. Turn the adjustment cap on the relief valve clockwise
one complete turn (360°).
8. The relief valve is now set correctly to 69 bar (1000
psi). Lock the adjustment cap using the locking nut or
some other thread locker e.g. Loctite or similar.

High Pressure Pump Servicing Instructions – Page 14
Troubleshooting
The troubleshooting table is highly technical and specific only to the high pressure pump, not your Rainman
watermaker in general. In the vast majority of operational troubleshooting issues, you should utilise the
table in the general operations manual.

High Pressure Pump Servicing Instructions – Page 15
Maintenance Log