Difference in clack valves

[timg]

Hi all,
I have two different water feed clack valves from an injector and axle pump.
On the left one the ball is allowed to move freely whereas on the right a shaft limits it's travel.
It's hard to tell which one allows more air to pass.
Any idea which one should be for the injector and which is for the ap?
Thanks

[dfh]

Aug 25, 2022 12:13:57 GMT timg said:

Hi all,
I have two different water feed clack valves from an injector and axle pump.
On the left one the ball is allowed to move freely whereas on the right a shaft limits it's travel.
It's hard to tell which one allows more air to pass.
Any idea which one should be for the injector and which is for the ap?
Thanks

You will find some information on clacks and ball lift in this article.

ibls.org/mediawiki/index.php?title=Design,_Care_and_Feeding_of_Check_Valves

David

[ettingtonliam]

Clack valves normally have restricted lift for the balls, probably about 5/64" for a 1/4" ball. I don't understand what you are saying about which one allows more air to pass. There shouldn't be any air in the water feed, just water!

I've no experience with the rod type restrictor, so couldn't tell you which one is suitable for the injector, and which for the axle pump, if indeed it makes any difference.
What size are these clacks?

[timg]

Aug 25, 2022 15:19:12 GMT ettingtonliam said:

Clack valves normally have restricted lift for the balls, probably about 5/64" for a 1/4" ball. I don't understand what you are saying about which one allows more air to pass. There shouldn't be any air in the water feed, just water!

I've no experience with the rod type restrictor, so couldn't tell you which one is suitable for the injector, and which for the axle pump, if indeed it makes any difference.
What size are these clacks?

Thanks, I meant air as in when I blow through it to see which is giving greater resistance. I think I read somewhere that injector clacks allow more water through than for one from an axle pump,

[ettingtonliam]

I see! Someone more knowledgeable than me will almost certainly be along shortly to answer your question!

[miken]

Looking at your picture I would guess that the one on the right is the injector valve.
The only reason I say that is that many years ago there was a series in the "Model Engineer" about injectors.
The author (Laurie Laurance) said that he would never fit a right angle clack direct to a boiler and always fitted an inline valve just below a dummy right angle fitting.
Your valve on the right looks like a compromise between the above. I see it as a vertical inline valve incorporated into an elbow.
Also,
When I made you those shim washers the other week, I'm pretty certain that the clack valve that you brought round my place was the one on the left.
Don't know if that's relevent.
MN

[timg]

Thanks Mike,
I think you're on to something here I've tried everything else to get the injector to work. 

[miken]

When you ran you new loco at HP earlier this year everything worked well I think I remember?
If so, then I think the first check is to see if there is an obstruction in the injector. They are easily blocked by debris.
There will be a small cone that should be a push fit in each end.
If you can remove these (don't mix them up) you should be able to see clearly through them.
Often they are tight.
I have a special pair of pliers I have adapted to grip the cones on my injectors without damaging them.
Also, make sure you have the injector fitted the right way round.

[uuu]

On "Jessie", the injector clack has smaller innards than the axle pump one.

Wilf

[flyingfox]

Greetings, I have heard it suggested that injectors need a larger ball lift than pumps.
Regards
Brian B

[Roger]

Since a pump needs the valve to re-seat on every stroke, I'd be inclined to fit the one with restricted lift on that one so that it closes more quickly. An injector just opens the valve and keeps feeding, so it's not really important to restrict the lift.

[timg]

Thanks all for your advice, I'll try it the other way round and see how I get on.

[timg]

So I ran steam test after lunch today and it turns out the one on the left works fine with the injector. At 40psi it was singing like a cheerful chiripin' budgie!

[miken]

I look forward to seeing it run at HP.

[timg]

Aug 29, 2022 7:46:23 GMT miken said:

I look forward to seeing it run at HP.

I hope to be there this Saturday with it

[doubletop]

I was of the view that the restriction of the lift is to stop the ball going too far and choking the outlet. A ball only needs to lift so far and then the flow is determined by the difference between the diameter of the ball and the internal diameter of the body. But I'd agree with Roger left is injector right is pump for the reasons he said.

Pete

[ettingtonliam]

Yes it is to prevent the ball from going too far, but it also stops the ball chattering on the seat which it can do if the lift is too much. Thats my experience anyway, others may differ!