§ 1065.644 — Vacuum-decay Leak Rate

This section describes how to calculate the leak rate of a vacuum-decay leak verification, which is described in § 1065.345(e). Use the following equation to calculate the leak rate, , and compare it to the criterion specified in § 1065.345(e):

Eq. 1065.644-1

Where:

Vvac = geometric volume of the vacuum-side of the sampling system.

R = molar gas constant.

p2 = vacuum-side absolute pressure at time t2.

T2 = vacuum-side absolute temperature at time t2.

p1 = vacuum-side absolute pressure at time t1.

T1 = vacuum-side absolute temperature at time t1.

t2 = time at completion of vacuum-decay leak verification test.

t1 = time at start of vacuum-decay leak verification test.

Example:

Vvac = 2.0000 L = 0.00200 m

3

R = 8.314472 J/(mol·K) = 8.314472 (m

2·kg)/(s

2·mol·K)

p2 = 50.600 kPa = 50600 Pa = 50600 kg/(m·s

2)

T2 = 293.15 K

p1 = 25.300 kPa = 25300 Pa = 25300 kg/(m·s

2)

T1 = 293.15 K

t2 = 10:57:35 a.m.

t1 = 10:56:25 a.m.