Alarm and Pump Performance Monitors

[ClarkBart]

Hi:

I was wondering what peoples experiences have been with the new class of Alarm and Pump performance monitors. Several manufacturers are making these such as Mission Communications and Raco.

I am wondering if the pump performance data such as gpm, starts and run time being provided is reliable. I have one installed and a pump station and am trying to get some sense on whether I should rely on the data or should I start collecting this data in the old fashioned way.

Thanks for any observations/opinions.

 

[SteveWag]

We have installed about 30 Mission 800 units, 90% monitoring duplex sewage lift stations. I have not used the calculated flow numbers. Run time and starts are 100% accurate. One of our clients also monitors motor running current and claims it to be a valuable trouble shooting tool. I think the flow number generated can be accurate but only if the wet-well geometry and on-off span is accurate (and not changed by the operator). I don’t know what will happen if the Lead pump fails and the Lag is operating. I think the calculation is based on emptying and filling a constant volume.
Steve

 

[ClarkBart]

Thanks Steve:

The unit that I have installed is also monitoring a duplex pump station using float controls with constant speed pumps. I have notice some significant anomalies in the flow rate and starts. The station has been typically having about 100 starts per day (50 per pump). There seems to be a upward creeping trend on the starts and flow rate with no corresponding change in pump run time. We had a relay go bad and one pump was off. I expected to see the pump that was on double its number of starts but it did not. There was no significant change in flow in the system based on other methods of monitoring the flow. Once the second pump was returned to service, the starts and flow rates for both pumps returned to what they were prior to the relay failure. There appears to be some trouble in the way that the pump performance data is collected and reported.

Have you had the opportunity to review the data from the Mission units that you've had installed under similar circumstances?

Given that the flow rates are calculated in these units with no calibration, I would expect that the best use for the flow rate estimates are trending and significant changes in short periods of time. It might be helpful for the Manufacturer's of these units to publish how the rates are calculated. I am a little concerned about using the data for management decisions given that there appears to be a lot of processing of the data with out any information being provided to the users about how that processing effects the numbers reported.

Thanks, Bart

 

[Artisi]

Without having a lot more detail, the comment " I expected to see the pump that was on double its number of starts but it did not. There was no significant change in flow in the system based on other methods of monitoring the flow." could indicate a pump hydraulic selection not being correct - seems one pump may be capable for keeping up with the inflow. Just shooting the breeze with something to think about.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[bimr]

I would expect that the control system is very accurate.

There may be a number of things that explain what you have witnessed. For example:

The flow to the lift station may be changing seasonally.

Both pumps may not be operating at the same flow capacity because of wear or fouling.

The pumping rate of the pump(s) may be changing as the discharge head that the pump is pumping against varies.

You should expect only 10% more capacity (than one pump) when both pumps are operating at the same time unless the pumps are selected to operate against a higher discharge head. Putting another pump online may not significantly affect the numer of pump starts.

The groundwater elevation may change seasonally and affect the I/I and lift station operation.

There is most likely a valid reason for the way that the lift station is operating, not an error in the data.

 

[ClarkBart]

Thanks Artisi:

The typical way to refer to a pump station with two pumps is a duplex pump station. I prefer the to think of them as a simplex pump station with 100% reserve pumping capacity. One pump can handle all of the flow. The pumps alternate from pump 1 to 2 after each pump down cycle to continuously exercise the 100% reserve capacity. The two pumps do not operate at the same time except under extreme circumstances. So, if one pump is not operating, the one that is takes the entire load because it does not alternate to the other pump.

A pump station that has 100 starts/day alternates each of the two pumps, 50 on pump 1 and 50 on pump 2. If one of the pumps is not operating, then pump that is should have 100 starts (in theory). In practice, this might be different because of the system controls and how the one pump that is operating activates. If pump 1 is off, then pump 2 comes on as the lead pump in one cycle. In the next cycle, it comes on as a lag pump. This means that it is likely pumping a greater volume, and slightly fewer pump cycles. The total pump starts may not exactly double with one pump disabled, but it would be close.

Anyways, I appreciate your thoughts. Thanks

 

[ClarkBart]

Thanks Bimr:

Yes, I understand the points you are making and they are valid considerations. But, there are obvious errors in the data being reported. I have not shared the name of the manufacturer because I do not want to drag them through the mud. I am trying to understand what experiences other people have had with these performance monitors independently of the manufacturer or sales reps. I've attached a file of the reported data for those that are interested.

 

[bimr]

Yes, there does appear to be some questionable reporting. You should question the reporting software and the assumptions being made in the software. The data is probably correct, but the data may be being reported incorrectly.

 

[SteveWag]

To see one of our clients monitoring setups, go to;

http://www.123mc.com/

In the upper right hand corner of the screen USERNAME “ Bedford “
PASSWORD “ 12345 “
Omitting the quotes.

A map will appear with red and green boxes. These are monitored sites. To the left is a box with menus. Click on “Data”, under “Pump Info”, “RunTimeTable” see the stats and calculated flow rates for Pump 1 and Pump 2. Be aware that this system also controls the operation of some potable water sites, not all are duplex sewage lift sites.

The problem is that the flow calculations are based on the LEAD On-Off elevations of the LEAD pump. This is not necessarily correct, suppose that the LEAD START has failed and the pumps are operating between the LAG ON and OFF. In this system, control of the pumps is by a device that is not part of the monitoring system.

Anyway, the password given is for visitors to an actual (my) system. You are welcome to look around. Note the pump operating current (Amps) information. The Operator seems to find that info very helpful.

Steve