MAC MAC155L, Instruction Manual

Page: 53 / 143

©Copyright MAC Instruments 2005. All Rights Reserved. MAC155 Rev. 12
Pg 37
L
Use ordinary distilled water to fill the tank. Do not use de-ionized water
6. Tighten the mounting clamp, close the cover, and turn power on to the
instrument.
SAMPLING PUMP
The purpose of the sampling pump is to circulate a sample of the atmosphere
that is being monitored through the sensor. The pumping action of a peristaltic
pump is created by compressing the tubing with a rotating cam. This
compressing action along with the movement along the axis of the tubing pushes
the air through the tube. Over time this tubing can become worn and will need
replacement. Replacement tubing can be obtained from the factory. The
sampling pump is driven by a 15 RPM motor (one revolution every 4 seconds).
This low speed combined with the sturdy construction of the pump assures a
long life.
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 in the following way:
1. Disconnect all electrical power to the MAC155 Probe.
2. Open the cover. Disconnect the silicone rubber hose from the sensor
and connect the intake port of the pump. (The intake port is located on
the right side of the pump) 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 module,
and close the cover. The instrument can be returned to service.