Back Pressure Regulator

The back pressure regulator looks at the other side than the Pressure Regulator: it holds the pressure at its input. As long as the input network is below the set value, it stays shut. Once it rises above, it lets the surplus through to the output.

That gives two typical uses:

• Overpressure protection: whatever pushes a network past a limit flows into a relief line – for example into a waste tank or outside through a Passive Vent.
• Priority: one line is filled up to a minimum pressure first, only then does gas move on to the next line.

Setting is the pressure in kPa at which it opens – from 0 to 60,795 kPa, which is also what Maximum reports; factory value 50 kPa. On the device you set it in steps of 100 kPa, holding the key for small increments in steps of 1 kPa, or directly as a number with a switched-on labeller in your hand. Per tick it lets through at most the surplus above the target. It does not check the pressure at the output: it pushes the surplus even into a network with higher pressure. On and Lock switch it; power and data share one port; base draw is 100 W.

A calculation on the limit of gas pipes: a network holds at most 60,795 kPa and counts as stressed from 80 %, i.e. about 48,636 kPa. Overpressure protection should trigger well below that so warming still has room – with the same amount of gas, pressure rises in the same ratio as the temperature in kelvin.

It comes from the same kit as the pressure regulator, the Kit (Pressure Regulator) from the Hydraulic Pipe Bender. Placing takes one step. More on how the parts differ in Pumps, valves and pressure regulators: which part for what.