MAC MAC155H, Instruction Manual

Page: 63 / 143

©Copyright MAC Instruments 2005. All Rights Reserved. MAC155 Rev. 12
Pg 47
The calibration gas flow path and the water tank can be checked for leaks in
the following way:
1. Disconnect the tubing that goes between the water tank and the
calibration pump, at the pump end. Use a “tee” fitting and connect a
pressure gauge to this line and then connect a clean piece of tubing
that you can blow into.
2. Blow into the tubing to pressurize the components, and then pinch the
tubing closed to hold the pressure. The exact pressure is not
important. Check that the pressure holds and does not leak away.
NEVER apply more than 1 psi / 7 kP to the water tank.
The tank may rupture at pressures above 1 psi / 7 kP
The calibration pump can be tested as described in test M3. If the calibration
pump is working properly, and the water tank, tubes, and fill plug are not leaking,
the reference gas must flow into the barrel when the pump runs.
M3 Sampling pump test
A new pump can produce a vacuum of approximately 8 psi / 55 kP. The
pump will perform properly as long as it can produce a vacuum of at least 0.5 psi
/ 3.4 kP. The pump can be tested as follows:
1. Disconnect all electrical power to the MAC155 Probe.
2. Open the cover. Disconnect the silicone rubber hose from the sensor
head fitting and connect the hose to a vacuum gauge that can display
a reading as low as 0.5 psi / 3.4 kP.
3. Re-connect power to the MAC155 Probe and note the reading on the
vacuum gauge after the pump starts to operate. A reading of 0.5 psi /
3.4 kP vacuum or more indicates that the pump is operating properly.
4. Disconnect electrical power, reconnect the hose to the sensor head
fitting, and close the cover. The instrument can be returned to service.