Motorised valve to fit 90mm OD pipe

[ChrisR]

Or even more conventionally, use a standard pump-set flow switch and pressure vessel. Like a negative head shower pump.
The pump keeps say over 2 bar in the pipe and pressure vessel.
Use ordinary float operated inlet valves on both the two tanks.
You can feed the garden tank from the water tower if you want, or direct from the pumped line.
The pump turns off when the flow stops.
Why you use a 90mm pipe to fill a garden watering tank I have no idea. The flow through a one inch valve, with 1 bar behind it, is pretty high. Higher if the inlet is connected to the pump outlet.

Why use a garden tank at all? How do you get the water out of it?

 

[Hooo]

A low level switch in the house tank starts the pump. The tank fills above the overflow pipe, and the garden tank is filled by the overflow. A high-level switch in the garden tank stops the pump. Easy.

Sorry, I should have supplied a bit more information. The water tower is 200m away from the garden tank. A bit too far to run the overflow pipe!

Use ordinary float operated inlet valves on both the two tanks.
Why you use a 90mm pipe to fill a garden watering tank I have no idea.
The flow through a one inch valve, with 1 bar behind it, is pretty high
Why use a garden tank at all? How do you get the water out of it?

I had a look for 90mm float valves, I couldn't find any.
I didn't design the system, it's a relic from the previous owners. The property used to be a farm.
The garden tank is about 10 to 15 cubic metres, and it takes a while to fill even with water coming out the 90mm at a good rate. I don't know what the flow rate through a one inch valve is, but it's got to be about a tenth of the 90mm one. I can't see it being enough.
I think the tank was originally put in to run irrigation further down the hill, now it's pumped to sprinklers in the garden.

 

[AlanE]

Presumably the existing set up means the tanks are refilled from virtually empty but with two large float valves tanks will start to refill from the moment water is started to be removed from them so slower flow rate may not be so significant.

 

[Hooo]

Flow rate is still pretty significant. That 10 to 15 cubic metre tank gets emptied every day, you need a decent flow rate just to match the rate it's being used.
Also, it's not just flow rate:
1. Putting small valves on will greatly increase the pressure in the pipework and load on the pump - and the condition of these is unknown, so I don't want to risk stressing them.
2. Fitting a float valve to the water tower would be a job in itself.
3. In this system the pump would be regularly cycling, rather than one long run once or twice a day. I'm sure that continuous cycling is not the best way to run a big 3 phase pump.

I appreciate all your efforts to try and work out an alternative system, but I really want to stick to a "if it works don't muck with it" philosophy. With the big valve and pump switch I'm just replacing two manually operated components with automated versions. This involves the minimum interference to the system, and so the least chance of problems. It I can get the valve for £230 then I reckon that's my best bet.

Thanks to all for the useful tips.

 

[doitall]

The cheapest valve would be GF pvc-u etc

http://ecat.georgfischer.com/mediac...age=catNav&catalogId=1102fdc172f2fa74&lang=en

The real problem is size, Uk BSP sizes are 80mm and 100mm so some adapter would be needed.

 

[Agile]

It works like this. A borehole pump fills a watertower for the house, and a ground level tank for the garden. When the water stops in the house, someone goes out and finds one of the workers who wanders down and switches the pump on (about half a mile away). After a while he notices that the water tower is overflowing, so he wanders to the garden tank and opens a gate valve in a pipe Td off the main feed. Since the water tower is about 10m higher, all the water now flows into the tank. Sometime later he notices that the tank is overflowing, and he wanders down and switches the pump off.
?

Perhaps there is something that I am missing here!

All you need is a float switch which turns the pump on when the garden tank level falls below say half full and then the same on the tower tank. Both connected in parallel !

Connect the garden tank to be filled by an overflow from the tower tank and the pump to only supply the tower tank.

If either tank falls below half full the pump is then turned on to refill !

Where is this exactly? Perhaps I could come and have a look during my holiday in August?

Tony

 

[Hooo]

The cheapest valve would be GF pvc-u etc

http://ecat.georgfischer.com/mediac...age=catNav&catalogId=1102fdc172f2fa74&lang=en

The real problem is size, Uk BSP sizes are 80mm and 100mm so some adapter would be needed.

Useful looking site, thanks. I'll give them a go.
I'm not sure if the size is odd, the pipe is 90mm OD and about 80mm bore. I'll probably end up with a 3" bore and an adaptor of some kind. I'm hoping I can get something that ends in steel, then we can just weld it onto the existing pipe, and not worry about it matching exactly.

 

[Hooo]

Connect the garden tank to be filled by an overflow from the tower tank and the pump to only supply the tower tank.

The water tower is 200m away from the garden tank. A bit too far to run the overflow pipe!

 

[doitall]

The standard PN flanges for 21/2", 3" will fit with a gasket.

You could use a nipple to make the connection

 

[Hooo]

The standard PN flanges for 21/2", 3" will fit with a gasket.

You could use a nipple to make the connection

Do you mean a 3" flange will fit my pipe? That's what I was hoping. Weld on a flange and fit a 3" valve.

I had to google to find out what a nipple was
Can you get steel nipples? That would work.

 

[doitall]

Yes you can get steel nipples in galv or black.

And no it won't fit 90mm, you will have to adapt something, it may with luck fit inside the existing pipe and be welded.

Bss or pipeline are your best stockest.

 

[Onetap]

Sorry, I should have supplied a bit more information. The water tower is 200m away from the garden tank. A bit too far to run the overflow pipe!.

Bums.
It was too easy, wasn't it.

In which case, look at www.Sontay.com. They do butterfly valves and a standard (Belimo) actuator, which they also sell, should be capable of turning it. Note the operating torques for the valve sizes and the differential pressure. Also note the cautions about sand and debris increasing the torque.

The wafer type butterfly valves have to be sandwiched between two flanges, or else you need a lugged valve suitable for end-of-line service.

There's a 2" butterfly valve on E-bay at present. I don't think the extra resistance imposed by a smaller valve would be significant compared with the head and frictional resistance of the old pipes.

Use ordinary float operated inlet valves on both the two tanks.
Why you use a 90mm pipe to fill a garden watering tank I have no idea.
The flow through a one inch valve, with 1 bar behind it, is pretty high
Why use a garden tank at all? How do you get the water out of it?

I had a look for 90mm float valves, I couldn't find any.
I didn't design the system, it's a relic from the previous owners. The property used to be a farm.
The garden tank is about 10 to 15 cubic metres, and it takes a while to fill even with water coming out the 90mm at a good rate. I don't know what the flow rate through a one inch valve is, but it's got to be about a tenth of the 90mm one. I can't see it being enough.
I think the tank was originally put in to run irrigation further down the hill, now it's pumped to sprinklers in the garden.

The problem with float valves is that they close slowly. It would work if it was set up so that the electric float switches in both tanks, wired in series, cut off the pump before the float valve closed fully. Any one float valve closing would divert flow to the other tank and the pump would stop before both valves closed, deadheading it.

 

[WDIK]

if it helps? originally i was confused with the OD dimension 90mm?

so anyway checking my tables reveals it as 3" black band. 88.9mm OD

which is odd as thats high press steam rated.

I would have expected blue band

 

[WDIK]

am I right in thinking this is crop irrigation?

 

[Onetap]

if it helps? originally i was confused with the OD dimension 90mm?

so anyway checking my tables reveals it as 3" black band. 88.9mm OD

which is odd as thats high press steam rated.

I would have expected blue band

Is it galvanized?
Black steel shouldn't be used for potable water.
Galvanized shouldn't be welded.