Presuretrol question

JM_2

What is the low limit on the main scale of a subtractive honeywell PA404A1xoA1 pressuretroll? The main scale has markings at 5-10-15 psi but it does not say what the bottom of the scale is.

Also if i put a new gauge on the pigtail ( the old gauge is shot and in a bad place, I am just going to leave the old one where it is) can i use a Brass "T" or does it have to be black steel to prevent galvanic corosion. The local hardware does not carry black that small, but they have brass or bronze i think it is bras.

thank you
john mahoney

Thank you.