"Foot pump" for shock arrestor (expansion vessel)

[dave22]

I will probably need to top up the pressure in a shock arrestor (expansion vessel) soon, which is placed in the mains pipe between my water meter and combi boiler.

The shock arrestor is one of the spherical ones, about the size of a tennis ball. After about 6 years, I started getting severe water hammer in the mains when turning taps on/off, and a chap from British Gas sorted it out during his annual visit by repressurising the arrestor with a foot pump of some sort. The pump had a pressure gauge built in. It's now been another 4 years or so, and I think the water hammer is gradually coming back.

1) Where can I acquire the appropriate pump with pressure gauge?
2) Does this "foot pump" have a special name?
3) What is the correct procedure? (What pressure is needed, and do I need to turn off the mains & release mains pressure by opening a tap before repressurising? I can't quite remember.)

Thanks,
Dave

 

[Terry7556]

1) in a shop like halfords
2)yes foot pump or its little brother bicycle pump
3)over 1 bar, part two yes

 

[muggles]

Good luck accurately repressurising one of these, they're so small you lose a lot of the pressure you've put in when you pull the pump off the valve. It can be done, but it's easier to replace it...

 

[ianmcd]

Dave this only needs a normal foot pump with a pressure guage or any other description of a pump with the same connection, yes turn off the water main and leave an outlet tap open then pump up to whatever the pressure requirement states on your mini expansion vessel a very easy fix

 

[dave22]

Many thanks for all replies; I hadn't realised it was just a standard foot-pump with a normal connection. I had assumed a special sort was needed in order to connect to a shock arrestor - evidently not!

Is it common for these shock arrestors (spherical type, tennis ball size) to need pressure topping up every few years?

Dave

 

[Terry7556]

its normal yes whether they are small like yours or larger on a combi.they seem to becoming more costly as well. the one on my sons powermax is £70 retail price

 

[DP]

Dave, the volume of air in the vessel is insignificant. You will be able to pressurise the vessel with even a mickey mouse air pump, BUT the moment you remove the connection, the vessel will be flat again. Either take the vessel to a petrol forecourt or use a motorised airpump to do the job and disconnect with pump running when pressure reached.

The posters who think it can be done with a foot pump, not being cheeky here , but have you tried? As Muggles says, you will loose the pressure when you disconnect the pump.

 

[dhutch]

Never done one that size, tennis balls are not big, but ive done a 1 liter one before with a normal hand pump and that was ok.

Another option is a mountain bike shock pump, designed for air sprung suspension. They dont have very much volume (wich you dont need anyway) but are designed to close the valve before they are removed (various methods of releasing the valve pin while still connected) so that no air escapes.

As £15 odd, cheaper a decent airline, and easier than de-plumbing it to take it to an airline.


Daniel