Monitoring a diesel water pump.

[Nigel Goodwin]

OK, I'm after a little info, if anyone has had any dealings with diesel powered water pumps?.

This is the information, as far as we know it so far.

We've been contacted to see if we can provide a solution for one of our water industry customers, they have a number of remote (Scotland, so VERY remote ) water pumping stations which in case of an electricity failure (or main pump failure) automatically switch to a diesel powered backup pump, and the water company want notifying if and when this happens. Currently they have no notification, and the first time they find out is when whatever the pump is supplying stops, after the generator has run out of fuel - which is never good on diesel engines.

Obviously, we would need to use a GMS modem to send a txt or an email, and I'd probably do it (as I often do) by connecting to a web server that runs a PHP script, that stores the information in a MYSQL database (so there's a record of what's happened), and sends one or more emails, to addresses stored in the same MYSQL system. This allows easy changes to the system, without needing to go out on site, and update the transmitters.

That's all fine, the issue is how to detect the diesel pump has fired up?.

We've no specs on the pumps, know nothing about them, and are currently waiting for then to arrange a site visit (or multiple site visits) to see what is there, and what we can use for detection.

Presumably electrical power will be no issue, as there's mains (until it goes off), and that could be used to keep the GMS batteries charged, or it could be powered from the batteries which are 'presumably' used to start the diesel pump.

One obvious (and easy) solution, would be to send a message when the mains electricity dies, but that doesn't tell them that the diesel pump is working, which I suspect is important to them?.

My thoughts are:

1) Detect electric power has gone off - send message informing of this.

2) Diesel pump has started running - send message confirming this.

3) Electricity has come back on, diesel pump has stopped, send message about this.

4) Electricity is still off, diesel pump has stopped (out of fuel?), send message about this.

So does anyone know, would such a diesel water pump have some easy way of detecting if it's running, like for example, do they have a light that shows they are running?.

I'm presuming the pumps are fairly large?.

 

[ZipZapOuch]

Is the pump outdoors? That remains to be seen.

IF the pump is outdoors, a microphone will be subject to environmental noise and weather conditions.

A waterproof industrial accelerometer could be used - an ICP-type with integral signal conditioning (ICP is a registered trademark of PCB Piezotronics). Some types have a DC output proportional to broadband (overall) vibration level. An ICP-type accelerometer requires a constant current power supply of 2–5mA with a compliance voltage of 18 – 27 volts. Plan on about $100 for this type of accelerometer.

As an alternative to an optical 1/rev detector, a magnetic pickup with a small magnet glued to the pump's shaft.... or possibly 2 magnets 180° apart to maintain balance. Like the optical method, this is also a low cost solution that's simple to monitor.

Even if it's indoors, spiderwebs, dust, oil vapor and bog dust will all be blowing around the diesel engine. Optical sensors should be limited to nearly-hermetically sealed devices like laser printer housings (and even those are known to get contaminated by paper fibers).

 

[rjenkinsgb]

Another option is to fit a vehicle knock sensor to a spare bolt location - they are designed for the engine environment and are functionally a linear vibration transducer.
(And far cheaper than other industrial vibration sensors!)

https://www.opieoils.co.uk/p-122333-bosch-knock-sensor-0261231197.aspx

 

[Nigel Goodwin]

Lot's of interesting ideas being bandied about

Environment wise, I'm presuming they are all outside, in the wilds of Scotland

Unfortunately we're still waiting for the customer to arrange site visits, it seems best to actually be there and discuss it with the customer.

It really depends on the exact situation, and exactly what we have access to - I would have thought simply sending a message if the electrical power went off would probably be all they need to know?. The issue seems to be the diesel kicking in, and no one knows, until it runs out of diesel and the water supply stops

There's probably no actual need to know the diesel has started, just that the electrical pump has stopped? - in either case, some kind of action is required.

Obviously if the diesel pump starts automatically, then it must detect the electrical pump failure somehow?, possibly there may be a connection we could tap in to.

There have been suggestions of a flow meter, to detect if the flow of water has stopped - this would probably be very easy to do, as there will VERY probably already be a water meter measuring the water (so they can charge accordingly). This water meter will most likely be fitted with a pulse sensor, and probably feeding a logger that sends in periodic water readings - I generally set ours to do this weekly, usually on Friday mornings. So we could fit a splitter on the pulse output of the meter (a large part of our business is making and selling splitters), or even build it in the GMS/GPRS device, in order to feed the existing logger, and our device as well. But this would probably just be an 'extra bonus', as once water has stopped flowing, the pump has already run out of diesel.

I'm considering adding multiple options.

1) Send a message that electrical power has been lost - VERY simple to do.

2) Send another message the diesel pump has fired up, a nice ON/OFF indicator light would be good for that, as would a pulse feed to a tachometer. The microphone/vibration suggestions could be an idea as well.

3) Send confirmation the pump is still supplying water.

 

[Diver300]

For engine running / not running, an oil pressure switch seems the most simple. You could get a t-piece for not much money and have a separate oil pressure switch for the monitoring and avoid any interface issues with what is already there.

Fuel level seems important to me to report, because it would be something that the users can understand easily, and it's something that they have to manage, and gives a good idea of how soon that pumping station needs attending to. It's also the only thing that will change over time when the diesel pumps are running, rather than relying on historic records for when the pump ran and when the fuel was filled up.

 

[Nigel Goodwin]

For engine running / not running, an oil pressure switch seems the most simple. You could get a t-piece for not much money and have a separate oil pressure switch for the monitoring and avoid any interface issues with what is already there.

Fuel level seems important to me to report, because it would be something that the users can understand easily, and it's something that they have to manage, and gives a good idea of how soon that pumping station needs attending to. It's also the only thing that will change over time when the diesel pumps are running, rather than relying on historic records for when the pump ran and when the fuel was filled up.

So far the only requirement is a message if the diesel pump starts up, as currently they have no information until the water stops flowing, then they have to refill the pumps and prime the entire fuel system.

The current contract only has about five years to run, so they don't want to spend a LOT on it, as they have already spent 10's of thousands with no useful results.