Manifold Pressure

[ectofix]

There wouldn’t be any manifold gas pressure if the burners were OFF.  Maybe I’m misunderstanding your question.  Burner manifold pressure is per the spec data plate.  MANIFOLD pressure is sometimes referred to as OPERATING pressure.  Hence – it’s the pressure you want to see when the burners are ON.

 

The manifold (operating) pressure is established by either a line regulator (internal or external of the appliance – depending on how it’s configured.  Usually it’s external though.) OR…the internal regulator within the combination valve in the appliance.

 

So, if you’re wanting to test manifold pressure on say…an atmospheric fryer (open burners with no induced air), you read gas pressure from the pressure tap in the manifold that feeds all of the burners.  So if the data plate says 4″WC, then that’s what you want to set the pressure regulator to when the burners are ON.  That’s what the data plate says.

 

If you’re testing manifold pressure of a six burner range w/standard oven, the same expectations apply.  To test THAT, be sure ALL burners are ON while you’re establishing the proper operating (uh…MANIFOLD) pressure.  Also be sure that when you turn each burner OFF, the pressure remains relatively close to the same for the rest burners that are still on.  That will prove that the regulator is doing its job.

 

What’s equally important but usually not shown on the data plate, is the SUPPLY pressure requirements of the appliance.  There are minimum expectations that you need to memorize as the standards that are drilled into technician’s brains:

 

For natural gas-supplied kitchens, you want 7″WC minimum to be fed to the appliance. For LP gas-supplied supplied kitchens – 11″WC minimum to be fed to the appliance.

 

Those are the pressures fed to the back of the unit.  If there’s a line regulator there, then to THAT.  The regulator establishes the MANIFOLD pressure to most ranges (that lack a combination valve).  In units with a combination valve, then ITS regulator steps the pressure down.  The maximum SUPPLY pressure is normally 1/2 psi…or about 13.5″WC (More reading about that can be found here> What is the gas pressure for Natural Gas?)

 

LASTLY – when you’re testing for proper pressure at a given appliance in a full-blown restaurant kitchen, you should fire up everything else on the cook line before doing your pressure testing.  This needs to be done to ensure that, when everything is also running, the MAIN gas supply is adequate and not starving *whatever-it-is-that-you’re-testing*…of ITS gas.

 

THAT last statement delves into the realms of proper gas supply line sizing…which requires ANOTHER few pages to explain.

[olivero]

Hey Ectofix,

 

Thanks for the extensive answer, you answered my question which was what the manifold pressure is, if its with burners on or off. That was my question, so thank you for the answer.

 

Yeah, sizing takes a bit more, been there and done it, know what you mean lol.