Canned Pump Protection (Electrical) 5

[controlnovice]

We are specifying canned pumps for several services in the near future. We are discussing (read: arguing) about the various protection levels for the pumps.

Options:
1. Temperature switch in the bearings and/or windings. We will be using this as I believe this is a standard.

2. Level switch. This is new to me. It is said that the pumps need to verify that it is full before being started. Any comments?

3. Power Switch (low and high). I've installed these on Mag pumps, but not canned pumps. The mechanical engineer requested power switches on canned pumps now also, but I'm not sure I agree. Essentially these will be in the 10-20hp range.

Are there any standards out there to indicate what protection is needed on a canned pump?

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This is normally the space where people post something insightful.

 

[rmw]

Used in a lot of acid services, among others. Acid services can be in lots of places, many of them non classified areas.

rmw

 

[pennpoint]

Be sure you specifiy the pumps rated capacity at the proper Hz. 50 vs. 60.
You may end up canned with your canned pumps.

Best regards
pennpoint

 

[54494060]

This has been an interesting thread. I've been following along for a couple of days without time to add my experience with "Canned Pumps". Several years ago, we had what we called canned pumps in a system called CVCS (Chemical Volume and control). These were small horse pwr. high speed (3600 RPM) combination "in-line" pump/motors. The rotor as well as the stator were sealed with I think about .020 stainless steel. The in-line pump/motor was flanged at both inboard/outboard to the piping and could not be run dry. Flow had to be established prior to operating the "canned pump. Thus, the control for the system was integrated with level (vol. tank), temperature (stator), and flow logic. Glad to be a part of this discussion.

12 fish
As iron sharpens iron, so does a man sharpen the countenance of his friends

 

[resqcapt19]

I have installed a few of these pumps where a motor power monitor was used to provide protection against running the pump dry.

http://www.loadcontrols.com/products/pmp_25_products.html

Don

 

[seanatkinson]

The point about a canned pump and hazardous areas is that there is no mechanical seal. Thefore 1 likely leak point is eliminated and the hazardous zoning of the space around the motor can sometimes be re-evaluated to a less hazardous zone. For mag drive pumps the motor is not in the liquid, the motor is "normal" and coupled to the pump impeller by magnetic attraction, not with a solid mechanical shaft. There is a very sucessful protection for dry running based on measuring the temperature of the barrier plate between the magnet and the impeller. Just measuring the level is not always enough, as you can damage the pump by having liquid in the pump but with the valves closed. Also an excellent indicator for incorrect pump running is the power factor of the electrical load. The power factor at dry running or dead head (all valves closed) is significantly lower than normal load and this can be used in the protective relay design