I have an Aqualung Conshelf XII regulator. The first stage has three ports. One that has my pressure gauge attached to it is stamped HP. Two are not stamped. One is for my primary second stage. The other is for the BCD fill/AIR II. How do I know which ones are LP or HP? Which devices have to hook up to what? If my reading is correct, my primary second stage should be hooked up to a high pressure port. And I'm guessing that the ports that are not stamped are LP. Does that mean my second stage has been wrongly connected to a low pressure port all these years?
difference between high and low pressure ports
- Thread starter bnaudie
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H2Andy
Contributor
hi... pressure gauges (and consoles with an SPG) hook up to HP. you can tell because if you look at the hose end on the gauge, you will see a TINY, TINY hole.
regulators and the BC hose go into the low pressure ports, and you can tell because the end of the reg hose will have a HUGE opening on it.
and don't worry... they won't screw into each other's sockets, so you can't screw it up (hehehehe... sorry).
make sure that if you are not using any port, it is covered with a screw-in plug with a working o-ring.
regulators and the BC hose go into the low pressure ports, and you can tell because the end of the reg hose will have a HUGE opening on it.
and don't worry... they won't screw into each other's sockets, so you can't screw it up (hehehehe... sorry).
make sure that if you are not using any port, it is covered with a screw-in plug with a working o-ring.
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bnaudie:
The HP port is exposed to the pressure exerted on your first stage by the air in the cylinder ... anywhere from 0 psi all the way up to 3500 psi. The only thing you connect to this port is your pressure gauge, and its purpose is to let you know how much pressure is in your air supply.
LP ports are exposed to what, in your first stage, is called "intermediate pressure". This is regulated, and is typically on the order of 130 to 150 psi. These ports are for connecting "everything else" ... which includes your second stage, octopus, and inflator hose(s) for BCD and/or drysuit.
You don't have to worry about misconnecting things ... the LP port opening is smaller than the HP port opening, so the threads on the HP and LP hoses won't work in the wrong type of port. Although HP and LP hoses look similar, they are built very differently. LP hoses are typically rated up to 250 psi, while HP hoses can be rated as high as 5000 psi.
Hope that helps answer your questions ...
... Bob (Grateful Diver)
I had some questions about 1/2" and 3/8" LP ports, and I guess this thread is sorta relevant.
How do you know what kind of threading you have on your reg, short of measuring it myself? I want to order some new hoses, but I can't figure out if my ScubaPro Mk2+ uses 1/2" or 3/8". ScubaPro's website is no help.
How do you know what kind of threading you have on your reg, short of measuring it myself? I want to order some new hoses, but I can't figure out if my ScubaPro Mk2+ uses 1/2" or 3/8". ScubaPro's website is no help.
Boogie711
Guest
Archman - dude, if you're confused, just measure it. It's not tough. 
Boogie711:Archman - dude, if you're confused, just measure it. It's not tough.
Er, being a pansy life scientist, tools are foreign to me. I think all my specimen rulers are in metric... must be a conversion formula around here somewhere. Crud.
captain
Contributor
Go to the hardware store and ask for a 3/8 X 24 fine thread bolt. If it screws into the port it's a 3/8. By the way most older regulators used the same 3/8 size on both HP and Lp ports.
Captain
Captain
Spectre
Contributor
life scientist huh?archman:
Ok. Stick your pinky finger in it. If it goes in; it's probably 1/2 inch. If it doesn't... 3/8.
If you have to cram the hose into the plug and need aqua seal to make it stay there, you're attempting to hook up a LP hose to a HP port.
Bad manuever my captian. Me thinks a visit to the LDS may benefit you.
In all seriousness. if it's not labeled HP or HFP (high flow port) then it's usually LP.
Bad manuever my captian. Me thinks a visit to the LDS may benefit you.
In all seriousness. if it's not labeled HP or HFP (high flow port) then it's usually LP.
archman:
Scubapro uses the industry standard 3/8" for low pressure ports on all their regs.
Regs made in the last 30 years will use a larger 7/16" size for the HP ports. There were a lot of problems in the distant past with divers attaching LP accessories to the HP port on the first stage when they both shared the same 3/8" size port.
HP ports also usually have a very small orifice in them to limit air loss in the event a hose fails and can be identified in that manner in addition to the 7/16" size and "HP" marking next to the port.
A few companies have recently used a larger 1/2" LP port for second stages. The idea is to provide more airflow to the second stages. It really is not needed as more than enough air can be efficiently passed through a regular 3/8 fitting and hose. The large size causes some problems getting proper hoses in remote locations and usually just results in a larger and stiffer hose to the second stages with no real benefit (although some owners who are proud of that particular feature on their regs may disagree). Dacor is one manufacturer who dropped the 1/2 LP port idea and I don't think there is any major risk of it ever becoming an industry standard.
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