Question

An atmospheric line on an indicator card from the head of a double-acting, single stage horizontal ammonia compressor is used

(A) to record piston stroke.
(B) to record volumetric efficiency.
(C) to record compressor superheat.
(D) as a pressure reference or standard.

Answer 1

The atmospheric line on an indicator card from the head of a double-acting, single stage horizontal ammonia compressor is used as a pressure reference or standard.

Step-by-step explanation:

The atmospheric line on an indicator card from the head of a double-acting, single stage horizontal ammonia compressor is used as a pressure reference or standard. (D)

When a compressor compresses a gas, the pressure inside the compressor cylinder increases. The atmospheric line on the indicator card represents the reference pressure or the pressure outside the compressor cylinder, which is usually atmospheric pressure.

The atmospheric line is used as a reference to compare the pressure inside the cylinder at different points in the compression cycle.