How Does A Vaporiser Work?

[rob99]

Evening

As some of you know I have been having issues with my vaporiser not controlling the gas pressure as it should.

Took it apart to have a look (It's a Zeta S) and I think I have the gist of it but could use some help.

As I see it there is a big spring with a diaphragm pushing on a lever which lets the liquid gas into a chamber. This liquid vaporises and pushes on the diaphragm which then closes the valve until the pressure gets low enough to allow more liquid gas in. The vacuum connection does some magic on the other side of the diaphragm to control the gas pressure according to how heavy your foot is on the loud pedal.

The issue I have seems to indicate that either the diaphragm is leaking or the valve doesn't seal correctly.

The diaphragm seems intact and the rubber on the valve seems ok so what causes this issue?

The rubber gasket on the water side looks a bit crinkly but otherwise seems ok.

Could one of you gents give an explanation of how this thing works or point me in the right direction.

Thanks Rob

[rossko]

It works like wot you said.
Debris under the rubber valve seal will cause overpressure, and may disappear during dismantling. Pinholes in castings are not unknown. Other types can get mechanically gummed up, but not usually a Zeta issue.
As I understand it, this Zeta is fairly new, and they are not problematic - I would be looking for that kind of cause. Or perhaps something odd with the vacuum pipe - collapsed, or a flap torn up internally at a push-on end.

[rob99]

Hi Rossko

Thanks for the reply.

I checked the rubber seal on the control valve and it seemed to be ok. There was a bit of rubber seal hanging off on the water gasket side where the liquid gas entry is, but it did look to be sealing. If it was leaking here then it would of leaked into the coolant system.
I also checked the vac pipe and it was pulling vacuum with no obvious leaks. The pipe is the very flexible silicone type about 3 foot long. have you ever known it to collapse and seal under high vacuum conditions.
One other thing is the vaporiser overpressure outlet is plumbed straight into the manifold, is this correct?

Thanks Rob

[LPGC]

One other thing is the vaporiser overpressure outlet is plumbed straight into the manifold, is this correct?

Thanks Rob

Probably not causing the problems, but try disconnecting it or plumbing it to the none-vacuum side of the throttle body.

Simon
www.Lpgc.co.uk