Red Propane Regulator - Why?

Stefonius wrote:

DiskDoctr wrote:
I didn't see anyone post the purpose of a red (1st/single stage) regulator, though some hinted at the workings.

I wonder if the OP's rig came with the "Generator Prep" package. The red regulator is used to supply propane to a built-in LP genset, and the regulator would be present in the system if the unit was prepped for a generator by the factory.

No I've had a generator in all my 5ers and they run off regulated gas downstream of the changeover regulator. The red regulator is on the LP tank distal from the automatic changeover regulator. Gas downstream of the red regulator goes directly into the changeover regulator.

DiskDoctr wrote:
I didn't see anyone post the purpose of a red (1st/single stage) regulator, though some hinted at the workings.

I wonder if the OP's rig came with the "Generator Prep" package. The red regulator is used to supply propane to a built-in LP genset, and the regulator would be present in the system if the unit was prepped for a generator by the factory.

Mile High wrote:


They are cheap regulators, and are a hazard greater than what they are trying to overcome - 2 of mine have leaked. I just remove them altogether.

I had this same thing happen in our Forest River Sierra. I went to a local RV parts place that's been around since they created dirt, and they said the same thing. Get rid of it. It's more dangerous then not having it.

Never noticed a difference in operation. Your results may vary.

Old-Biscuit wrote:

Mile High wrote:
Actually it provides back pressure on the on the cylinder furthest from the main regulator, to prevent the safety valve from slamming shut if you open it too fast. Didn't used to be an issue until the design of the cylinders changed to the high flow safety shutoff.

They are cheap regulators, and are a hazard greater than what they are trying to overcome - 2 of mine have leaked. I just remove them altogether.

The excess flow shut-off is in the hose......not in propane cylinder.
Propane cylinder does have a spring loaded valve that closes when hose is disconnected. Can not get flow from cylinder without hose attached.

Yes there is ball check in the hose, and there is an OPD, but there is also an excess flow check valve in the cylinder valve:

Check Valve - The check valve is designed to gauge the pressure of the gas as it leaves the propane cylinder. Because the gas grill should have all valves in the "off" position when the gas is turned on the pressure stops at the valve and is re-checked by the valve at the tank. If there is a leak or if the grill control valves are in the "on" position pressure is released and the pressure checked at the valve is different. When this happens the check valve is designed to stop gas flow through the valve. The problem with the check valve is that it is very sensitive and when a tank is full, with the additional pressure of the OPD float pushing on the liquid, the gas can push through the check valve so strongly it checks the check valve by mistake. This happens frequently.

I didn't see anyone post the purpose of a red (1st/single stage) regulator, though some hinted at the workings.

A propane bottle stores propane at a high pressure, too high for normal consumption, and keeps a large amount of the propane in liquid form.

The normal propane appliances use low pressure propane vapor, not liquid.

Regulators reduce the high pressure to low pressure.

But....the catch is this pressure reduction (and volume expansion into low pressure gas form) can cause a substantial cooling effect inside the regulator.

For small volumes, not a problem. For higher volume appliances, multiple appliances used at once, or colder outside temps, this can cause freeze ups of the regulator.

Splitting this process into '2 stages' with a red 'high pressure' regulator, then a final low pressure regulator, can reduce this problem and deliver a higher, often more reliable gas flow.

There are '2 stage regulators' that look like a double regulator, but are one unit. But there is no reason these two stages cannot be separated by a length of tubing/pipe.

Think of it this way. Bottle is storage, red/1st stage/high pressure is used for (high volume or "inside") distribution, and 2nd stage/appliance inbuilt/low pressure is for final consumption.

For houses, it is not permitted to run unregulated lp within the structure (directly from bottle/tank). It MUST be reduced at least to 1st stage. It is common to have a 1st stage regulator at the tank or on the outside of the building, thenn thee line enters and branches throughout the building, then have multiple 2nd stage regulators near the points of consumption.

I don't know if that is the same reasoning for DOT regs or what they are, but it would make sense ;)

The important thing is NOT to mix lines of different stages of regulation, and NEVER NEVER NEVER send un-regulated lp to an appliance that does not have the proper regulator.

Mile High wrote:
Actually it provides back pressure on the on the cylinder furthest from the main regulator, to prevent the safety valve from slamming shut if you open it too fast. Didn't used to be an issue until the design of the cylinders changed to the high flow safety shutoff.

They are cheap regulators, and are a hazard greater than what they are trying to overcome - 2 of mine have leaked. I just remove them altogether.

The excess flow shut-off is in the hose......not in propane cylinder.
Propane cylinder does have a spring loaded valve that closes when hose is disconnected. Can not get flow from cylinder without hose attached.

Actually it provides back pressure on the on the cylinder furthest from the main regulator, to prevent the safety valve from slamming shut if you open it too fast. Didn't used to be an issue until the design of the cylinders changed to the high flow safety shutoff.

They are cheap regulators, and are a hazard greater than what they are trying to overcome - 2 of mine have leaked. I just remove them altogether.

OK guys, thanks for the input. What I have discovered is two things. One, the off side regulator is a DOT requirement. Two, my propane system is plumbed wrong, thus causing the regulator to fail. In a three bottle system, the two unregulated bottles are teed together and go into one side of the auto changeover regulator, the regulated, off-side bottle goes into the other side of the auto changeover regulator. Done.

GASMAN6674 wrote:
It is to keep the propane vapor from the 3rd curb side tank from turning back to liquid in the line. Under the correct temperature and pressure (anything over 20psi)propane vapor can turn back to liquid. Yes it is a safety feature

Normal propane cylinder pressure can be 150#-200#.
Red Regulator drops cylinder pressure down to 30# before crossing over to the main 2 stage regulator that drops pressure down to 15# (1st stage) and then down to roughly 0.4# (11" WC) 2nd stage outlet feeding propane system.

It is to keep the propane vapor from the 3rd curb side tank from turning back to liquid in the line. Under the correct temperature and pressure (anything over 20psi)propane vapor can turn back to liquid. Yes it is a safety feature