Suctioning fuel from liquid condensate trap failing

Look here for answers to your technical questions. Post a question or share your expertise with others.
MMendoza
Pump Jockey
Posts: 5
Joined: Fri Aug 28, 2020 5:50 pm

Suctioning fuel from liquid condensate trap failing

Post by MMendoza » Fri Aug 28, 2020 6:15 pm

Hope someone can help with troubleshooting issue of not drawing enough vacuum from RJ STP to extract fuel from liquid condensate trap (LCT) located one floor down and approximately 230' from the tank location (i.e. the tanks are installed on street level and they feed dispensers on a subterranean garage level thus the need for vapor pot)

1/4" copper line feeds into the LCT and per vapor recovery testing the fuel introduced into the vapor pot should be extracted within 20 minutes and we cannot meet that for some reason.

Copper line is connected via the functional element at the turbine. All components I mean all components have been replaced and multiple in-line siphon valves have been added to try and increase the vacuum. Currently reading 15-16" Hg of vacuum only. Leaks have been checked for with no issues, debris has been checked and nothing in the lines. Need any ideas?

petrodood1
Head Tech
Posts: 129
Joined: Thu Apr 27, 2006 6:56 am
Location: North East Ohio, Cleveland Area

Re: Suctioning fuel from liquid condensate trap failing

Post by petrodood1 » Mon Aug 31, 2020 3:47 pm

How long has this site been operational, and how much vertical lift is there? You said your using 1/4" line, we usually use 3/8" line. Has the site passed a blockage test before?
Are you here to raise the prices?

I thought it would work even though the sign said "OUT OF ORDER"

It's come to me over the years that orange cones are idiot attractants.. :P

User avatar
1onemarty
Head Tech
Posts: 390
Joined: Thu Feb 02, 2012 8:51 am
Location: Chicago, Phoenix, Houston, Seattle, Milwaukee, Madison.

Re: Suctioning fuel from liquid condensate trap failing

Post by 1onemarty » Mon Aug 31, 2020 5:40 pm

MMendoza wrote:
Fri Aug 28, 2020 6:15 pm
Hope someone can help with troubleshooting issue of not drawing enough vacuum from RJ STP to extract fuel from liquid condensate trap (LCT) located one floor down and approximately 230' from the tank location (i.e. the tanks are installed on street level and they feed dispensers on a subterranean garage level thus the need for vapor pot)

1/4" copper line feeds into the LCT and per vapor recovery testing the fuel introduced into the vapor pot should be extracted within 20 minutes and we cannot meet that for some reason.

Copper line is connected via the functional element at the turbine. All components I mean all components have been replaced and multiple in-line siphon valves have been added to try and increase the vacuum. Currently reading 15-16" Hg of vacuum only. Leaks have been checked for with no issues, debris has been checked and nothing in the lines. Need any ideas?
You could have a blockage in the S Tube that goes down into the gas from Under the STP head, could also simply be the Functional Element, have you tried another one if you have Pull the STP and Check the S Tube that runs down, probably blocked..Have you by chance replaced the O-Rings under the Functional Element? Are you using Flare fittings, or Compression fittings? I personally go flare fittings whenever working on that type of project. I know you said you already checked for leaks at this time though.
Marty's Petro Services :evil:

MMendoza
Pump Jockey
Posts: 5
Joined: Fri Aug 28, 2020 5:50 pm

Re: Suctioning fuel from liquid condensate trap failing

Post by MMendoza » Tue Sep 08, 2020 2:42 pm

You could have a blockage in the S Tube that goes down into the gas from Under the STP head, could also simply be the Functional Element, have you tried another one if you have Pull the STP and Check the S Tube that runs down, probably blocked..Have you by chance replaced the O-Rings under the Functional Element? Are you using Flare fittings, or Compression fittings? I personally go flare fittings whenever working on that type of project. I know you said you already checked for leaks at this time though.

Thanks for the reply OneMarty:

We can check the S tube, but we've replaced the motor to max 1.5 HP, and the S tube looked fine during replacement; replaced all o-rings and the functional element, and we use compression fittings. We've conducted multiple leak tests to make sure everything is snug, no blockage, no debris, but still not pulling enough. Granted the LCT is about 230 feet from the UST's so I'm not sure it'll ever have enough pull. It's just a mystery.

MMendoza
Pump Jockey
Posts: 5
Joined: Fri Aug 28, 2020 5:50 pm

Re: Suctioning fuel from liquid condensate trap failing

Post by MMendoza » Tue Sep 08, 2020 2:49 pm

petrodood1 wrote:
Mon Aug 31, 2020 3:47 pm
How long has this site been operational, and how much vertical lift is there? You said your using 1/4" line, we usually use 3/8" line. Has the site passed a blockage test before?
Thanks for the reply Petrodood:

Hard to know how long these subterranean dispensers have been operational, I'd guess since the 80's at least. The USTs sit at street level and the LCT sits below the dispenser island so overall I'd say the total vertical lift needed is initially 10' from the LCT to the ceiling of the subterranean garage, goes almost 180' to the subterranean wall, then elevates another 10' up to the tank sumps so overall 20' feet or so of vertical lift needed. The suction line is 1/4" ID with 3/8" OD. LCT blockage testing has always been spotty, but yes it has passed before.


ZMiller
Head Tech
Posts: 1017
Joined: Sun Jul 15, 2007 10:53 am
Location: Atlanta/Phoenix/Sacramento

Re: Suctioning fuel from liquid condensate trap failing

Post by ZMiller » Wed Sep 09, 2020 8:18 am

Old or newer style Functional element? Max Vacuum adjusted?
When you are dead it's likely you won't know it. It could be difficult for others. It's the same if you are stupid.
"Tact is the ability to tell someone to go to Hell in a way that they will begin looking forward to the trip"

stuppid
Head Tech
Posts: 159
Joined: Thu Dec 23, 2010 7:10 am

Re: Suctioning fuel from liquid condensate trap failing

Post by stuppid » Wed Sep 09, 2020 9:23 am

I could be wrong but I think you can only pull gasoline about 14' vertical. Any higher lift and the negative pressure in the tube causes the gasoline to flash to vapor state.

MMendoza
Pump Jockey
Posts: 5
Joined: Fri Aug 28, 2020 5:50 pm

Re: Suctioning fuel from liquid condensate trap failing

Post by MMendoza » Wed Sep 09, 2020 12:06 pm

ZMiller wrote:
Wed Sep 09, 2020 8:18 am
Old or newer style Functional element? Max Vacuum adjusted?
The functional element is the newer style with max adjustment knob at max vacuum

MMendoza
Pump Jockey
Posts: 5
Joined: Fri Aug 28, 2020 5:50 pm

Re: Suctioning fuel from liquid condensate trap failing

Post by MMendoza » Wed Sep 09, 2020 12:09 pm

stuppid wrote:
Wed Sep 09, 2020 9:23 am
I could be wrong but I think you can only pull gasoline about 14' vertical. Any higher lift and the negative pressure in the tube causes the gasoline to flash to vapor state.
Interesting response. We didn't consider the science of the extraction, and in this case I'm not sure the design engineers did either. Do you know where I can find literature on gas applications regarding suction? Where does that 14' vertical number come from? I'm not an engineer, but I'd like to have something to tell my client on why things aren't working.

ZMiller
Head Tech
Posts: 1017
Joined: Sun Jul 15, 2007 10:53 am
Location: Atlanta/Phoenix/Sacramento

Re: Suctioning fuel from liquid condensate trap failing

Post by ZMiller » Thu Sep 10, 2020 10:22 am

Negative head and vaporized gasoline? I have in the past found an (usually in a junk pile or gathering dust on a back shelf) old Healy Jet 100 and installed in containment at pump making available 100 inches of vacuum.
When you are dead it's likely you won't know it. It could be difficult for others. It's the same if you are stupid.
"Tact is the ability to tell someone to go to Hell in a way that they will begin looking forward to the trip"

Post Reply