Propane Tanks & Furnaces

[Onespeed405]

I have a question regarding propane tanks and my RV furnace.

This weekend, I had 1 full 30lb propane tank and one 2/3 full (30lb) propane tank on an automatic switch over valve. I had the switch over valve pointing to the 2/3 tank with the tank turned on. I left the full tank turned off. (I intended to turn it on later)

All propane appliances were working fine, except the furnace. The pre-blower would turn on, the burner would ignite for about 8-10 seconds, then fail and shut down. I lived with this the first night.

In the morning, I turned on the valve of the full tank, but did not touch the switch over valve.

Poof, the furnace worked as normal.

As it turns out, for the whole weekend, we still had 2 pounds left in the first tank and never dipped into the full one.

Anyone have an idea of what is going on here? I have been RVing for 30 years and have done this many times (running with one tank open).

[Me_Again]

Old-Biscuit wrote:
Believe what you want Chris..........


Patent Number US7967025 B2

Wow, so many wrong and only you right? Not!

[Old-Biscuit]

Believe what you want Chris..........


Patent Number US7967025 B2

[Me_Again]

Old-Biscuit wrote:

Me Again wrote:
Stop by and I will show you the weed burner tripping on several tanks I have.

http://www.nashwauk.net/understandingopdvalves.html

Chris

What he calls 'The Excess Flow Valve' in OPD is the spring loaded shutoff that does not allow flow w/o a fitting connected.....either POL or ACME. They hold that valve open allowing propane to flow. As long as the fitting is attached that spring loaded valve will remain open.

It is NOT an Excess Flow Device.........it is a Safety Valve that prevents propane from spewing out of a cylinder that is not connected.

Did you go to any of his links and read them...None describe an excess flow device in the OPD.
In POL and ACME but not OPDs

Better read this one!

http://www.qualitypropaneandfuels.com/faq.phtml

Why does my grill have a very low flame at times?

The new style of Overfill Protection Device valves have an excess flow safety feature built-in that limits the amount of propane allowed to escape the tank. Sometimes, the excess flow can slug shut if the grill valve has been turned on before the valve on the tank has been turned on or if the valve is opened too quickly. Simply shut off all off the valve on the tank, wait for 10 seconds, and start over. Turn the tank valve on very slowly, turn the grill valve, and light the grill.



Chris

[Old-Biscuit]

Me Again wrote:
Stop by and I will show you the weed burner tripping on several tanks I have.

http://www.nashwauk.net/understandingopdvalves.html

Chris

What he calls 'The Excess Flow Valve' in OPD is the spring loaded shutoff that does not allow flow w/o a fitting connected.....either POL or ACME. They hold that valve open allowing propane to flow. As long as the fitting is attached that spring loaded valve will remain open.

It is NOT an Excess Flow Device.........it is a Safety Valve that prevents propane from spewing out of a cylinder that is not connected.

Did you go to any of his links and read them...None describe an excess flow device in the OPD.
In POL and ACME but not OPDs

[Me_Again]

Stop by and I will show you the weed burner tripping on several tanks I have.

http://www.nashwauk.net/understandingopdvalves.html

Chris

[Old-Biscuit]

Me Again wrote:
The weed burner has the old style male end with no excess flow valve. It works fine on old style tanks, hard to get flow on OPD tanks.

On edit!

Found this:

New OPD style valves have several safety features built in. The least frustrating is the excess flow check valve on the tank side of the connection which is set high enough that it almost never matters. That said there is another excess flow valve in the QCC connection (the big plastic hand wheel that fits the outside threads of an OPD valve) which is color coded. Black ones are set to 55k btus, green to 200k and red to 400k. If either of these is closing you will hear it click. Just close the valve, wait a minute and reopen very slowly. If you think it’s stuck closed just bang the tank on the ground a few times then try opening it again.

Chris

Got a link to this OPD valve that has an Excess Flow Device?


YES....the ACME NUTS are color coded based on flow.

GREEN is used on RV pigtail hoses based on LP Regulator flow capacities.

[Me_Again]

The weed burner has the old style male end with no excess flow valve. It works fine on old style tanks, hard to get flow on OPD tanks.

On edit!

Found this:

New OPD style valves have several safety features built in. The least frustrating is the excess flow check valve on the tank side of the connection which is set high enough that it almost never matters. That said there is another excess flow valve in the QCC connection (the big plastic hand wheel that fits the outside threads of an OPD valve) which is color coded. Black ones are set to 55k btus, green to 200k and red to 400k. If either of these is closing you will hear it click. Just close the valve, wait a minute and reopen very slowly. If you think it’s stuck closed just bang the tank on the ground a few times then try opening it again.

Chris

[Old-Biscuit]

Me Again wrote:
So explain how come my weed burner that screws inside the service valve has problems operating on new OPD? Sneaking up it will run. Open fast and propane flow is restricted.

Because the POL fitting on the weed burner hose that screws inside the OPD service valve incorporates an 'Excess Flow Device'

NOTE: there ARE POL fittings that do NOT have excess flow device and are designed for full propane flow........which OPD service valve will allow.

[Old-Biscuit]

Onespeed405 wrote:
To: Old-Biscuit

Thanks for the info.

I have those green nuts. LOL

I was under the mistaken impression that the Excess Flow function was on the tank itself. Someone told me, that if you take a full, unconnected tank, and open the valve, the valve will shut down and no propane will escape.

I guess I should be careful of "school ground" educations.

Thanks, this was a helpful discussion.

The propane cylinder service valve has a spring loaded shutoff that will not allow propane to flow it service valve is opened WITHOUT a hose connected.
The ACME NUT has a 'stub' that opens/holds open this spring loaded valve when nut is crewed onto cylinder
The spring loaded valve is part of the OPD/service valve....which consists of:


2 types used.......this one with a vertical tube float and one that has a lever arm with float.

OPD does several things. Allows propane filling & discharge, shuts off filling at 80%, will not allow propane to flow w/o hose connected, has pressure relief valve and bleeder valve with dip tube at 80% liquid level.

ACME NUT has the other safety features so that together a portable propane cylinder is as fool proof as one can be made for 'consumer use'-----regular ole joe

[Me_Again]

So explain how come my weed burner that screws inside the service valve has problems operating on new OPD? Sneaking up it will run. Open fast and propane flow is restricted.

So have been off reading about the new OPD tanks. I believe the excess flow valve is part of the new service valve on the tank. The big green nut is designed to melt at 240 degrees and back out of the service valve shutting off gas flow. As noted above my weed burner has the old style connection and will trip the excess flow valve.

Chris

[Onespeed405]

To: Old-Biscuit

Thanks for the info.

I have those green nuts. LOL

I was under the mistaken impression that the Excess Flow function was on the tank itself. Someone told me, that if you take a full, unconnected tank, and open the valve, the valve will shut down and no propane will escape.

I guess I should be careful of "school ground" educations.

Thanks, this was a helpful discussion.

[Old-Biscuit]

Onespeed405 wrote:
To: Old-Biscuit

I know the OPD is designed to stop overfilling, but aren't these same tanks the ones you have to open "ever so slowly"? That feature is supposedly designed to stop a large spontaneous discharge if the valve (unconnected) opened up on a full "not empty" tank?

I kind of used the OPD as a generic label to describe these tanks.

I welcome your knowledge on the subject.

Read my previous post---above yours about OPDs and Excess Flow Devices.

Excess Flow Device is in the big green nut.......that is what trips (under several situations)

More about ACME NUT.....

[Onespeed405]

To: Old-Biscuit

I know the OPD is designed to stop overfilling, but aren't these same tanks the ones you have to open "ever so slowly"? That feature is supposedly designed to stop a large spontaneous discharge if the valve (unconnected) opened up on a full "not empty" tank?

I kind of used the OPD as a generic label to describe these tanks.

I welcome your knowledge on the subject.

[Old-Biscuit]

Onespeed405 wrote:
Thanks so far gang...

Just to further clarify...

There was a already a half day of full demand on the propane.
- hot water heater (always on)
- fridge on propane setting
- 3 burner stove and oven was used
- furnace trying to light


The switch over never turned red all weekend. It was turned toward the "in use " tank.

(New info)
Prior to the weekend I filled the spare "not in use" tank, hooked it up, but never turned it on. Maybe the lack of pressure on that side of the line mattered.

I also took off the "in use" tank to weigh it. (2/3 okay) Put it back on line, but (and I already knew better) I did not turn it on slowly. I did not think I tripped the OPD since water heater, fridge, stove worked fine.

Huh???

The OPD does NOT trip.....it is for refilling cylinder ONLY and is designed to stop overfilling.