FAQs
1. Are there any lubrication requirements for WMD or MD motors?
2. What is the difference between the MD and WMD version?
3. How often should I inspect the pump end?
4. What is a TEFC or TENV motor?
5. Why is the motor surface temperature so hot?
6. Why is the pump noisy?
7. Can I use different diameter pipe for connecting the pump to my system?
8. Can I replace the bearings in the pump?
9. What does a high pitched metallic noise coming form the motor mean?
10 Do you repair the motors?
11. Why did my MD model not have a plug when I received it?
12. Can I rotate the front casing of the pump?
13. What happened when I de-couple the pump?
Common Terms

1. Are there any lubrication requirements for WMD or MD motors?

No maintenance is required for either motor.  Both feature sealed for life ball bearings and there is no need for external grease or oil lubrication. (Top)

2. What is the difference between the MD and WMD version?

Hydraulically the MD and MWD series are identical.  They both use the same high quality precision injection molded Iwaki pump end, the only difference is in the motors.  The WMD series use domestically manufactured motors and a modeled adaptor between the pump end and the motor.  The motors are rolled steel construction and the entire assembly is approximately 3” longer than the equivalent MD.  The MD designs use motors manufactured in Japan.  They are aluminum cast construction and the pump end adaptor bracket is cast into the end of the motor.  This results in the overall shorter length of the MD design. (Top)

3. How often should I inspect the pump end?

If you are growing coral in your tank we would suggest an initial inspection 3 – 6 months after installation to determine how much calcium build up is occurring in the pump.  After this you can project how often the pump will need to be cleaned.  For most other applications an annual inspection and cleaning is all that is required. (Top)

4. What is a TEFC or TENV motor?

A TEFC motor is a Totally Enclosed Fan Cooled motor meaning there is an external fan (at the back of the motor) that blows air over the surface of the motor to cool it.  A Totally Enclosed Non-Ventilated motor does not utilize an external fan, the heat from the internal windings radiates from the surface of the motor.   Our 15-30 series use TENV motor designs, 40 – 100’s use TEFC motor designs. (Top)

5. Why is the motor surface temperature so hot?

In TENV motors all of the heat generated radiates from the motor surface.  You can place your hand on the motor, but it becomes uncomfortable after a shot period of time.  For TEFC motors the motor surface is cooler because the fan is blowing air across the motor to cool it.  (Top)

6. Why is the pump noisy?

Noise can result from many different sources. Some of the more common reasons for a noisy pump are; Air getting into the pump end, either from leaking fittings or a low water level in the sump.  A restriction in the suction line starving the pump resulting in cavitation.  Not enough backpressure on the pump allowing it to run out on its performance curve resulting instability and cavitation, a bad motor bearing – usually a high-pitched metallic sound.  (Top)

7. Can I use different diameter pipe for connecting the pump to my system?

Yes, different diameter pipes can be used, but simple rules should be observed.  Never use a smaller size on the suction or inlet side of the pump.  You should always use the same diameter if possible or larger if necessary.  The ideal situation is to have a straight run of pipe into the pump with no fittings to ensure a smooth laminar flow into the pump.  We realize this is not always possible but you should try to minimize the complexity of the piping on the pump inlet as much as you can.  On the outlet or discharge side of the pump you have more flexibility with respect to fittings, elbows, pipe size etc.  The pump works against the resulting backpressure, the more fittings smaller pipes etc equates to more backpressure.  The larger the pump, less number of fittings means there is less backpressure.   Every pump needs some backpressure so if your system is simple and there is not a lot of pressure the pump needs to overcome then we would suggest putting a control valve on the discharge side of the pump to “tune” the flow to optimize your pumping system. (Top)

8. Can I replace the bearings in the pump?

The bearings in the pump end are replaceable.  They are press fit into the front and rear casing.  To replace the bearings you simply replace the front or rear casing.  (Top)

9. What does a high pitched metallic noise coming form the motor mean?

A high-pitched metallic noise coming from the motor is indicative of a failed motor bearing.  When the bearing shield is compromised the lubricating grease escapes and the bearings start to make noise. (Top)

10. Do you repair the motors?

We do not repair motors.  For motors that fail under warranty we replace the entire motor assembly.  It is possible for small motor repair shops to replace bearings or capacitors. (Top)

11. Why did my MD model not have a plug when I received it?

Originally designs for the industrial market, the MD series include cord sets suitable for hard wiring.  A three-pronged grounded plug will need to be installed to use a standard outlet to power the pump.  Such plugs can be found at any hardware store such as The Home Depot. (Top)

12. Can I rotate the front casing of the pump?

The front casing can be rotated to any position the mounting pattern will allow.  Keep in mind if outlet is pointed down it will be harder for the pump to vent and air bubbles may show up in the discharge stream for a period of time longer than normal. (Top)

13. What happened when I de-couple the pump?

The pump uses a drive magnet mounted to a motor shaft.  This rotates on the outside of a cup like part, the rear casing or rearing housing.  Inside of this housing is the impeller mounted to another magnet, the driven magnet.  Under normal operation the magnets are “coupled”.  The inner rotates synchronously with the outer.  If a shell or a rock gets sucked into the pump and jams the impeller preventing it from rotating the pump will decouple.  The inside is stationary; the outer continues to spin on the motor shaft.  If this occurs the power should be turned off immediately.  The magnets will be weakened if the pump is decoupled so care should be taken to avoid this. (Top)

Common terms – Simple Explanations

Dead Head – Operation of the pump against a closed valve or clogged pipe on the discharge side.

Run out – occurs when there is not enough backpressure on the pump to maintain a flow rate within the pumps design.  A control valve on the outlet side can create backpressure to prevent run out.

Cavitation – When there is not enough pressure to prevent air bubbles from forming in the pump end.  Results in excessive noise and vibration.  Restrictions in the inlet line, leaks in inlet side of pump, or run-out operation are possible causes of cavitation.

Dry run – Running the pump without fluid in the pump end – not a good thing!.  Restrictions in the inlet (like someone shutting a valve) or checking if the unit powers up after wiring are common reasons for dry run. (Top)