1st stage Ports

[cbborromeo]

My appologies if this has already been posted, but I can't seem to find a good answer to the question of 1st stage ports. Regulator literature always lists different port configuration and I was wondering how it factors into selecting a first stage?

1. What exactly is the difference between Low Pressure and High Pressure ports?

2. What screws into LP ports and what goes into HP ports (e.g. 2nd Stage, Octo., Integrated Air Transmitter, BC hose, etc.)?

3. How important are the number of HP vs. LP when choosing a 1st stage?

4. Any other things to consider?

Thanks!

 

[Quarrior]

My appologies if this has already been posted, but I can't seem to find a good answer to the question of 1st stage ports. Regulator literature always lists different port configuration and I was wondering how it factors into selecting a first stage?

1. What exactly is the difference between Low Pressure and High Pressure ports?

2. What screws into LP ports and what goes into HP ports (e.g. 2nd Stage, Octo., Integrated Air Transmitter, BC hose, etc.)?

3. How important are the number of HP vs. LP when choosing a 1st stage?

4. Any other things to consider?

Thanks!

1. Difference is size, the HP ports are larger in size.

2. LP port gets the second stage hoses, BC inflator hose and drysuit inflator hose. HP gets the SPG and computer transmitter if you have a remote air integrated computer.

3. It's a good idea to have at least 2 HP and a minimum of 3 LP if you are not going to use the gear for drysuit diving, otherwise you need 4 LP ports.

4. There are many variables to consider when purchasing a reg. Most importantly is the climate you intend to use it in, now and in the future. I prefer a good quality environmentally sealed reg like the Zeagle DSV with the ZX second stage on both the primary and the OCTO. I also like an SPG with nice big numbers.

 

[Vie]

3. How important are the number of HP vs. LP when choosing a 1st stage?

It really depends on the hose routing configuration that you want to use and also whether you are using the first stage for single, doubles or deco. I find that the angle(s) of the ports is/are also quite important..

 

[Vie]

4. Any other things to consider?

Long term cost of and/or availability of service/spare parts. Some manufacturer offer "parts for life" and will continue to support discontinued products.

 

[H2Andy]

1. What exactly is the difference between Low Pressure and High Pressure ports?

high pressure ports have a larger diameter than low pressure ports. as the
name implies, higher pressure air is delivered through high pressure ports.

2. What screws into LP ports and what goes into HP ports (e.g. 2nd Stage, Octo., Integrated Air Transmitter, BC hose, etc.)?

your pressure gauge (or console) goes into the high pressure port.
everything else goes into the low pressure ports.


3. How important are the number of HP vs. LP when choosing a 1st stage?

you only need one HP (for your pressure gauge), but 2 HP's is standard
in most regs. how many LP's you need depends on wether you have a dry
suit, in which case you'll need 4 LP's:

primary reg
secondary reg
bc inflator
dry suit inflator

otherwise, just 3

 

[cbborromeo]

Ah, it all becomes clear now. Thanks very much for your responses!

 

[SDAnderson]

High pressure ports are a direct outlet for tank air. Though the gas passes through the first stage, the pressure has not been stepped down or regulated. The port itself is usually a little bit larger than a low pressure port, though not always. High pressure hoses should have flow limiting fitting (it looks like the inlet is just a pinhole) on the inlet side which serves to mitigate gas loss and injury potential in the event of a hose failure. They also normally have a special fitting on the outlet side that allows the fitting to swivel despite the high pressure. This fitting will have a small, hollow, removable post that everyone should carry a spare for. The HP port feeds your submersible pressure gauge (or console or air-integrated computer), allowing you to monitor the pressure in your tank.

The low pressure ports, on the other hand, are outlets that are regulated by the first stage. Instead of tank pressure, the gas coming out of a low pressure port will normally be in the 125 - 175 psi range, depending upon the first stage regulator and how it is adjusted. This reduced pressure is what feeds your primary and alternate second stage regulators, your BCD, your drysuit (if you use one), etc. Just to confuse you, the port is called a low pressure port but the pressure output is called the "intermediate pressure" because it will be further stepped down by your second stage regulator to approximately 15 psi above ambient - true "low pressure." The LP port is slightly smaller (most of the time, some Apeks, for instance, have a larger LP port) but the bore of the hose is actually much larger, to allow for a sufficient volume of gas flow.

You want at least one HP port and four LP ports. Many first stages come with an extra of each, always a nice thing to have.

 

[cbborromeo]

This has turned into a very educational thread, thank you!