Comments on: Keeping Wastewater Wells Clean – Relatively speaking

By: Scott Critchley

Scott Critchley — Mon, 17 Aug 2009 15:00:00 +0000

@Kaewen Tan Re the undercurrent snore detection, if a customer does not want to snore the pumps due to the issues mentioned, they need to set the parameters to avoid this. However, if undercurrent detection is enabled, the clean-out cycle will be stopped as soon as a snore is detected. Without it, bad programming of parameters, or changes in well conditions (inflow) will lead to an extended snore anyway, likely resulting in a undercurrent fault after snoring for much longer. The other possibility is that a snore will produce a current draw that will raise and fall as air and then water are pumped, and not drop the current for long enough for a full undercurrent fault, so the snore will continue as long as the delay is set.

By: Plumber Sydney

Plumber Sydney — Sat, 25 Jul 2009 04:27:14 +0000

Hey – great article. Stumbled upon it by accident but I’m glad I did. Will be back again daily. Cheers.

By: Scott Critchley

Scott Critchley — Fri, 20 Mar 2009 13:36:45 +0000

I like Kaewen’s proposal of using the calculated outflow rate to calculate the time to run on, so that it pumps a known distance. Great idea.

One of the concepts behind the sump clean-out feature was to pump out the grease that normally floats on top of the liquid; and to do this, the level would have to get down to pump snore level. I guess the customer will have to decide if they want to avoid the floating grease bricks or avoid snoring the pumps.

By: Steve Carson

Steve Carson — Fri, 23 Jan 2009 04:04:35 +0000

Hi Kaewen and Joe, thanks to both of you for your comments. It sounds like we shouldn’t introduce that feature – and probably should include a note in our manual about the safety margin.

By: Joe Evans

Joe Evans — Thu, 22 Jan 2009 22:16:58 +0000

Steve, I agree that under current will probably lead to air locking in many installations. We recommend that a cleaning cycle should stop when the level above the pump’s suction reaches 3X the suction diameter. Joe

By: Kaewen Tan

Kaewen Tan — Thu, 22 Jan 2009 15:32:54 +0000

Hi Steve,

The “Stop on under-current” would be a good idea, but it depends mainly on the configuration of the pump layouts. If a pump starts to snore, chances are likely the water level would be very low. This may cause air to be trapped in the vertical pipes and once normal cycles resumes, there is a high possibility of an airlock.
An alternative would be the ability to set a extended delay shut off delay every programmable preset cycles.

Another idea is to have a variable called “pump body” height (eg 0.6m). The controller would calculate the time taken for each point change in the multitrode probe. Lets say 30secs for every 0.3m on average for that cycle. So when the water level reaches the OFF point, the controller will run for another 60secs or less to cater for the 0.6m of water. A safety note to consider is that the pumps must have a cooling jacket if the water level is to be below 3/4 of the pump body.