So the pressure relief valve on my recovery tank blew recently. When it blew, it never shut again. It spewed LPG for hours and let out 50 lbs of gas. It never shut off. The seller of this tank ensured me that this is what the tank is designed to do. I've seen other tanks briefly release some pressure before closing again; isn't this what they're designed to do? Doesn't it make more sense, wouldn't it be safer if the release valve let out the excess pressure then closed? The seller claimed that it was engineered to just keep venting. I don't understand.Isn't it more dangerous and harder to contain shitloads of gas spewing into the atmosphere? Is the seller full of shit? If not, how is this safer than a valve that automatically closes and then reopens at a predetermined PSI? Thx.
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pressure release valve FAILURE!
- Thread starter HWY36
- Start date
That's really BS . When the pressure is exceed the set point of the pressure relief valve , the relief valve will automatically open it and let the over pressure out and then close if the pressure in the tank below the set point of the pressure relief valve . If the pressure relief valve won't close , all the gas will be gone ! That's crazy . Which brand you bought ?
All pressure relief valves are not created equal. Each valve has both a cracking pressure and a reset pressure, which are typically not the same. The cracking pressure is usually higher than the reset pressure, so if it releases at say 125 psi, it may not reset until 100 psi.
That said, there are also defective valves. What pressure did it release at and what pressure did it eventually reset at?
It released at 150; it never reset; the tank emptied and the valve is still open. The seller claimed that it was engineered that way and said I would need to purchase a new pressure relief valve. I wanted to see if there is any way on earth that is possible before I jump to any conclusions.
If you can recommend a reputable pressure release valve, that is something I would happily pay extra for. Regards.
I've used rupture discs only good for one failure, but never seen one time PRV tank valves.
What kind of tank and who did you buy it from?
We used Swagelok pressure relief valves, if you are looking for a reliable replacement.
I bought the tank from Open Source Steel, who, until now, I've been happy with. The guy's name was Dominick and he was a total dick. When I told him it didn't make sense for a PRV to keep spewing gas until it was empty, he insisted it was designed that way. He also told me I would need to purchase a new PRV and that he didn't want to argue about it. I want the world to know about this.
Thanks for the PRV suggestion
Thanks for the kind words. My balls have almost dropped back to their normal position; pretty scary shit. My pump went out and the tank had a lot of gas. The temp climbed quicker than I anticipated. Going to get a back up tank for the PRV to shoot the gas into for next time, god forbid. Any recommendations on where to get a tank other than Open Source Steel. Thx all.
https://dsps.wi.gov/sb/docs/sb-CodeDevComm41AdoptAppx85to106.pdf
Above is a link to ASME Section VIII, which outlines pressure relief requirements in UG 125 through 137.
Pressure Relief Devices/UG-125 General
(a) All pressure vessels within the Scope of this Division, irrespective of size or pressure, shall be provided with pressure relief devices in accordance with the requirements of UG-125 through UG- 137.
NFPA-58 definition of pressure relief devices and valves for LPG service.
https://www.nfpa.org/assets/files/aboutthecodes/58/58-98-pdf.pdf
Pressure Relief Devices:
A device designed to open to pre-vent a rise of internal fluid pressure in excess of a specifiedvalue due to emergency or abnormal conditions.
Pressure Relief Valve.
A type of pressure relief device designed to both open and close to maintain internal fluid pressure.
If you look at their ad, they are calling it a Pressure Relief Valve: https://www.opensourcesteel.com/products/copy-of-50lb-jacketed-solvent-tank
If they are selling this for LPG service, they ostensibly should meet the requirements for that service.
Thank you for the info. I will try and figure out a diplomatic way to let them know that IF what they're selling is designed to do what they claim, they are endangering people's lives. Given their initial response, I don't expect a warm reception.
After ALL the gas blew off (well after), I opened the return valve, coming from the heat exchange-going to the recovery tank to make sure that it was indeed the PRV that failed. It was. The PRV was still open and any gas that I vented into the recovery tank spewed out of the PRV.
https://www.opensourcesteel.com/collections/pressure-relief-valves/products/pressure-relief-valve
This is the PRV that Open Source Steel sells. I believe it is the exact same one that comes on the 100# tank. Anyone know if this is designed to reclose or just keep endlessly releasing pressure?
This is the PRV that Open Source Steel sells. I believe it is the exact same one that comes on the 100# tank. Anyone know if this is designed to reclose or just keep endlessly releasing pressure?
That looks to me like a pressure relief valve, as it is labeled, which is supposed to reseat and turn off once the pressure has dropped. A pressure relief device stays open.
If it is actually a device it is mislabeled.
It is also a very cheeep valve for that application. Not one that I would use.
If it is actually a device it is mislabeled.
It is also a very cheeep valve for that application. Not one that I would use.
To avoid a situation similar to highway 36; What if I plumbed the PRV on my main recovery tank to an access empty recovery tank to create a backup safety location for gas to recover. Im curious any thoughts on that kind of safety setup. Also should i put that extra recovery tank under negative pressure or would that negative pressure potentially pull on the PRV releasing gas from main tank ?
While that sounds like a good idea, and I originally designed a system that way, there is no guarantee with such a set up that it won't simply over pressure both tanks, so it was rejected when I went for certification to ASME.
Wouldn't two #100 tanks be more likely to disperse 150 PSI because there is more volume to hold the pressure?
I observed a shit ton of water in the bottom of the tank when it was done gassing off. Will that have any drastic effects on PSI?
If the second tank were large enough it clearly would work, but there needs to be protection in case it isn't large enough to keep the peak pressure low enough.
Perhaps a second tank to catch the over pressure, but a slightly higher pressure release on that tank as well.
