ball valve question

[johnf]

Can anyone tell me what's the difference between a 'Part 1' and a 'Part 2' ball valve? I was trying to get a replacement for a leaking toilet cistern ball valve (very old) that looks like a 'Part 1', but the only ones I can find of this design are for high (mains) pressure. I thought maybe that was what a 'Part 2' is for, but they only seem to be high pressure too. The space in the cistern is very restricted, so alternatives like a Torbeck or Fluidmaster valve won't fit. I'm a bit doubtful even a conventional plastic side-entry valve will fit, as I don't think the float arm is long enough to reach the free space beyond the siphon where the float needs to go. Is it possible to modify a 'Part 1' to make it suitable for low-pressure use?

 

[MANDATE]

Have a look at the screwfix site, they're both high pressure the old type is part 1 OK

 

[johnf]

Thanks Mandate. So are you saying it's OK to fit a high pressure valve, even though the cistern is fed from the cold water tank in the loft?

 

[oilman]

You'll have a very slow fill rate. The only difference between high and low pressure types is the size of the hole in the valve nozzle. These can be replaced seperately if needed.

 

[MANDATE]

BS 1212 show part 1 as piston type valves and part 2 as diaphram type valves. Those supplied by screwfix are both high pressure types.
You need a low pressure type if the water is coming from the water tank.
I believe some valves are sold with adaptors so you use the adaptor to suit your situation, or maybe when you buy a replacement valve nozzle both types may be available. I have seen replacement nozzles in B & Q for just less than £1 (plastic type, funnel shaped) but I didn't note if they were for high or low pressure.
As oilman says its the nozzle size that make the differance between pressure not part 1 or part 2.

 

[jofly24]

I am just getting the hang of different types of ball valves and would like to know if there is a significant difference between part one and two brass valves and the plastic type. What type should be fitted where?

 

[jofly24]

fluidmaster versus torbeck valves Are they identical? Are they as good as each other? Are they interchangeable?

 

[johnf]

I fitted one of each a few months ago (following the discussion above). I managed to squeeze a Torbeck valve into the cistern. It's pretty good, though not as silent as claimed, as a little water trickles out of a hole in the side of the valve body when it's filling. It appears to be the way it's designed, not a fault. The main water outlet is on top of the valve, which makes it taller, and it fouled the underside of the cistern lid - I had to glue a couple of strips of ceramic tile to the cistern lid to raise it slightly.
Straight after that, the ball valve in the cold water tank in the loft started leaking too. I'd already bought a Fluidmaster (to try in the toilet cistern), so I used that. I like the design of it - it's easy to adjust the float height, etc, and went in OK. The only drawback is my water tank doesn't have vertical sides, so the float touches the side of the tank at the bottom of its shaft. The screw section of the valve isn't long enough to position the valve far enough away from the tank side. But so far (about 6 months) so good - the float hasn't got stuck against the side of the tank... and it is MUCH quieter than its predecessor (conventional brass ball valve).
I have no idea about the long-term reliability of either of these. They are more complicated than conventional valves, and the fitting instructions for both suggest periodic dismantling and cleaning.