Water control issue

one2go · Sep 5, 2017

Saffa said:
Looking at your original post it sounds like they have tanks. Where do these sit in the system?

Tanks are placed like 50 meters from pump.

Pump-pipe-pressure transmitter-pipe- flow meter- pipe- tanks-system (figuratively).

They have calculated tanks to replace pump on low consumption. When pump is to strong on its 60% power (low consumption leads to high pressure) and goes to off state, then tank has to maintain desired pressure in pipeline

DwSoFt · Sep 5, 2017

Ok this is how I read this scenario. Let's see how I do.

As the flow rate varies I would say this is just a pressure control scenario. You.limit the high flow rate but other than that it will be controlling on pressure. (As others said you cant co trol pressure when demand is above regulated flow setpoint unless you allow it to.go above a bit) On the low consumption times I'd recommend a few different fixes. Install external cooling fan and motor so.you can slow the main motor down more or
Install recycle valve that at minimum speed it is still.maintaining pressure by recycling excess. (In this case I would also install a high high pressure sd incase of recycle valve problems.

Tom Jenkins · Sep 5, 2017

You need to find out what the actual process demand is based on. You mention cooling, which implies flow control is the real process variable of concern. Maintaining a constant pressure is just a way of keeping one valve's movement from affecting all other flows.

The way this is usually done is to have a cascade loop, where flow is adjusted to maintain pressure and speed or throttling is modulated to maintain flow. Once you hit max or min flow the flow control is clamped.

one2go · Sep 7, 2017

DwSoFt said:
Ok this is how I read this scenario. Let's see how I do.

As the flow rate varies I would say this is just a pressure control scenario. You.limit the high flow rate but other than that it will be controlling on pressure. (As others said you cant co trol pressure when demand is above regulated flow setpoint unless you allow it to.go above a bit) On the low consumption times I'd recommend a few different fixes. Install external cooling fan and motor so.you can slow the main motor down more or
Install recycle valve that at minimum speed it is still.maintaining pressure by recycling excess. (In this case I would also install a high high pressure sd incase of recycle valve problems.

They have installed 2 tanks whos duty is to maintain water supply when consumption is low. (e.g. when pump reaches minimum rotating speed and its still too powerful)

one2go · Sep 7, 2017

Tom Jenkins said:
You need to find out what the actual process demand is based on. You mention cooling, which implies flow control is the real process variable of concern. Maintaining a constant pressure is just a way of keeping one valve's movement from affecting all other flows.

The way this is usually done is to have a cascade loop, where flow is adjusted to maintain pressure and speed or throttling is modulated to maintain flow. Once you hit max or min flow the flow control is clamped.

Yes I agree.

Currently im doing on something similar.

Thanks.

DwSoFt · Sep 7, 2017

one2go said:
They have installed 2 tanks whos duty is to maintain water supply when consumption is low. (e.g. when pump reaches minimum rotating speed and its still too powerful)

I understand that but they aren't working then? So this is my solution

osmanmom · Sep 7, 2017

wrong post sorry

one2go · Sep 7, 2017

DwSoFt said:
I understand that but they aren't working then? So this is my solution

They are working but not as they are supposed to do.

Imo they are too small, because pump has maximum of 5 switchings per hour and those tanks cannot complete thier task. hm hm

Water control issue

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