How to test 25mm mdpe pipe

[Vinpetrol]

I done a job last year which has a pump installed in line on the 25mm mdpe pipe . It is situated in the garage .
The client has reported that the pump is now pulsating after being fine for months . The plumber has checked the pump and says there is a leak under ground . The set up is The water comes in from the boundary box goes into the garage, through the pump , back out of the garage and over into the house . It then is distributed throughout the house and has another mdpe that leaves the house and goes over to the garage to supply the washing machine . I then teed into the garage supply from the house to supply an outside tap (forgotten by plumbers) on the outside off the house .
It’s all been working fine with the pump loading the pressure up to 2.5 bar .
Then the clients reported to the main contractor that the pump was pulsating and that the water pressure was awful. The plumber says if he turns off the supply back to the garage and outside tap in side the house , then house all works fine .
It all points to a leak in my mdpe pipe from the house to the garage or where I’ve teed into it for the outside tap .
I’ve bought a gauge to pressure test my pipework before I start digging up the drive but I am thinking it is likely a leak unless the pump could be struggling once the extra load comes on but it is strange that all has been fine for six months . I also know that clients turned up the pressure that the pump supplies but surely the pump wouldn’t deliver enough pressure to blow a backfilled connected fitting apart .
Any thoughts ?

 

[JD450A]

Is there a pressure vessel in the system with a pressure type electrical switch controlling the pump?

 

[DaveDCB]

Chuck a online stopgap after the pump on the garage run, so you can pressurise that portion, then isolate - leave it a hour and see what you have on the outside tap( I assume you have a gauge that fits onto a 3/4 fitting?)

 

[Smiffy]

Chuck a online stopgap after the pump on the garage run, so you can pressurise that portion, then isolate - leave it a hour and see what you have on the outside tap( I assume you have a gauge that fits onto a 3/4 fitting?)

Squeeze off tool is best for this. No cutting the pipe can be installed in multiple consecutive locations and far easier to install in the bottom of a muddy hole if need be. Plus dead handy making the repair if it is live or if you inadvertently find the pipe with a digger bucket.

Pardon our interruption...

 

[V8Druid]

if you don't have a pressure vessel in the system, every time a tap is turned on the pump will fire up .... you could have a start capacitor issue on the pump .. have had it myself, 'til I installed a pressure vessel (and new capacitor) .. pump does not now run at every drop in pressure and runs longer once the vessel drops low enough, pressure wise, until fully charged again. could also be the pressure switch too mind ... they'm a PITA after a year or two,s operation .. I keep a spare for when the pump's going on/off/on/off.
MDPE pipe & fittings're good for 12 BAR IIRC safely, continuously ..... as long as you ain't forgotten to dog one, or one hasn't split

 

[JD450A]

Right, got puter keyboard now so I'll put some explanations in to the Pressure Vessel (PV) scenario.

1) - Pressure vessel bladder failure - The rubber bladder in the PV has split, leading to the system being unable to hold a charge. On a system with high demand this may well show up similar to a leak (Pump pulsating on and off) as the demand is far greater than the PV can supply in it's damaged state.... the flip side is on a low demand system with a large enough PV the air in the PV may be enough to work with a split bladder.... easiest way to fault check is to tap the PV and see if it sounds full of water, alongside letting out some air (tyre type valve in top) - If water is present the bladder has split.

2) - Lazy arse people and non existent PV or a PV that is unsuitable for the volume of water/pipework. - The PV is too small to work the system properly and thus pump pulsates on and off to meet demand......

2.5 bar is crappy pressure anyway IMHO. Sounds to me like a cheap arse pump?

 

[V8Druid]

Right, got puter keyboard now so I'll put some explanations in to the Pressure Vessel (PV) scenario.

1) - Pressure vessel bladder failure - The rubber bladder in the PV has split, leading to the system being unable to hold a charge. On a system with high demand this may well show up similar to a leak (Pump pulsating on and off) as the demand is far greater than the PV can supply in it's damaged state.... the flip side is on a low demand system with a large enough PV the air in the PV may be enough to work with a split bladder.... easiest way to fault check is to tap the PV and see if it sounds full of water, alongside letting out some air (tyre type valve in top) - If water is present the bladder has split.

2) - Lazy arse people and non existent PV or a PV that is unsuitable for the volume of water/pipework. - The PV is too small to work the system properly and thus pump pulsates on and off to meet demand......

2.5 bar is crappy pressure anyway IMHO. Sounds to me like a cheap arse pump?

mine runs on 1.5 bar quite happily .... 's enough to charge the boiler's system and provide decent pressure in a shower ... will also 'knock the bottom out' of the sink/splash everywhere, if you give it full on.

 

[Gecko]

If they admit to playing with the pressure switch, a burst pipe is a possibility.
A mate was quizzing me about his burst pipe - turned out his pressure switch was full of water and seized.

 

[Vinpetrol]

Is there a pressure vessel in the system with a pressure type electrical switch controlling the pump?

Apparently so , a digital one on the pump . I will know more on Thursday as I’m going through then for a look and to test the pipes in the ground

 

[Vinpetrol]

Chuck a online stopgap after the pump on the garage run, so you can pressurise that portion, then isolate - leave it a hour and see what you have on the outside tap( I assume you have a gauge that fits onto a 3/4 fitting?)

That’s my intention . I have gauge I can put on the outside tap to see if it drops

 

[Vinpetrol]

Squeeze off tool is best for this. No cutting the pipe can be installed in multiple consecutive locations and far easier to install in the bottom of a muddy hole if need be. Plus dead handy making the repair if it is live or if you inadvertently find the pipe with a digger bucket.

Pardon our interruption...

I have a clamp in the weapons box

 

[Vinpetrol]

If they admit to playing with the pressure switch, a burst pipe is a possibility.
A mate was quizzing me about his burst pipe - turned out his pressure switch was full of water and seized.

They have already admitted this . But I can’t see that a pump being wound up to full pressure would blow mdpe fittings apart . I’m assuming a pump would be limited to a pressure below the fittings connected to it

 

[Vinpetrol]

Chuck a online stopgap after the pump on the garage run, so you can pressurise that portion, then isolate - leave it a hour and see what you have on the outside tap( I assume you have a gauge that fits onto a 3/4 fitting?)

What you’re saying is isolate the house , then pressurise the rest ? If so I like this idea as it may highlight an issue if any at the pump

 

[Vinpetrol]

Chuck a online stopgap after the pump on the garage run, so you can pressurise that portion, then isolate - leave it a hour and see what you have on the outside tap( I assume you have a gauge that fits onto a 3/4 fitting?)

What you’re saying is isolate the house , then pressurise the rest ? If so I like this idea as it may highlight an issue if any at thebpui

Right, got puter keyboard now so I'll put some explanations in to the Pressure Vessel (PV) scenario.

1) - Pressure vessel bladder failure - The rubber bladder in the PV has split, leading to the system being unable to hold a charge. On a system with high demand this may well show up similar to a leak (Pump pulsating on and off) as the demand is far greater than the PV can supply in it's damaged state.... the flip side is on a low demand system with a large enough PV the air in the PV may be enough to work with a split bladder.... easiest way to fault check is to tap the PV and see if it sounds full of water, alongside letting out some air (tyre type valve in top) - If water is present the bladder has split.

2) - Lazy arse people and non existent PV or a PV that is unsuitable for the volume of water/pipework. - The PV is too small to work the system properly and thus pump pulsates on and off to meet demand......

2.5 bar is crappy pressure anyway IMHO. Sounds to me like a cheap arse pump?

Yes Rory , this is my train of thought . I’m not saying it’s impossible my mdpe joints may of failed . I just want to be sure they haven’t before I dig the finished driveway up and part of that is looking for alternate issues and your description above is exactly what the client is experiencing

 

[DaveDCB]

What you’re saying is isolate the house , then pressurise the rest ? If so I like this idea as it may highlight an issue if any at the pump

Yep. Like smiffy says use a squeeze off but a permanent isolator on a that run wouldn’t hurt, ie to cut that leg off over a hard winter etc.

 

[Steve]

There must be a one way non return valve in the supply before the pump which is unlikely to fail in 6 months. While the pump is running it creates suction on the supply but once the pump shuts off the pressure is greater on the pump side so will try to equalise back through the supply until the pump restarts. I have had this happen before but not on a system only 6 months old but I would check it before digging anything up.

 

[DaveDCB]

There must be a one way non return valve in the supply before the pump which is unlikely to fail in 6 months. While the pump is running it creates suction on the supply but once the pump shuts off the pressure is greater on the pump side so will try to equalise back through the supply until the pump restarts. I have had this happen before but not on a system only 6 months old but I would check it before digging anything up.

Yeah thinking about it, when my jetwash runs short of water the output starts to pulsate, sounds similar to your problem? I get what they are saying by the potential leak.. thus isolate it off just to prove it one way or another.

 

[doobin]

Main question- is the pui

if you don't have a pressure vessel in the system, every time a tap is turned on the pump will fire up .... you could have a start capacitor issue on the pump .. have had it myself, 'til I installed a pressure vessel (and new capacitor) .. pump does not now run at every drop in pressure and runs longer once the vessel drops low enough, pressure wise, until fully charged again. could also be the pressure switch too mind ... they'm a PITA after a year or two,s operation .. I keep a spare for when the pump's going on/off/on/off.
MDPE pipe & fittings're good for 12 BAR IIRC safely, continuously ..... as long as you ain't forgotten to dog one, or one hasn't split

This. Get a sparky to check the electrical side of things, if they mean that the motor on the pump is pulsing on and off.

I've just had this sort of problem on the supply at the yard. I fitted a new bladder and pressurised. After six months it started pulsing again- turned out the contacts in the switch were fked.

A leak will not lead to the motor pulsing quickly. A leak will mean the pump comes on, pressures up and the shuts off whilst you watch the pressure guage slowly drop, until it triggers the cycle again.

 

[Giles]

For the pressure test this is how I do it

Ended up with the flexvolt compressor as the tyre one took too long on 600m runs of 32mm

Average uk water is 2-4 bar so I took it up to 3 bar and left it an hour to check. We’d fusion welded our joints though.

Think compression are dn6 aren’t they? So should be fine if installed correctly

 

[V8Druid]

For the pressure test this is how I do it

Ended up with the flexvolt compressor as the tyre one took too long on 600m runs of 32mm

Average uk water is 2-4 bar so I took it up to 3 bar and left it an hour to check. We’d fusion welded our joints though.

Think compression are dn6 aren’t they? So should be fine if installed correctly

that set up needs a tap between the compressor line and the plumbing ... or a schrader valve and disconnect once pressurised ... will leak back through the compressor Giles