Thermo Scientific 10519, Instruction Manual

Page: 34 / 44

Chapter 5 Preventative Maintenance
5-4
FLOW LEAK CHECKING
This procedure enables the user to thoroughly check the controller for leaks. Leak
checking should only be conducted if the Model 200L Single Dilution Probe Controller is
suspected of performance calibration errors. Leak checking the controller ensures that the
unit does not produce erroneous readings on the gas analyzer. A leak check is performed
at the factory to ensure the proper operations before shipping to the customer.
Leak check the lines to the dilution probe (see Figure 2-5) before checking for leaks in the
controller. This is done by disconnecting the umbilical line between the controller and the
dilution probe, and attaching a pressure gauge to the end of the line that was attached to
the probe. Connect a shut off valve and pressure gauge to the end of the line, which was
connected to the controller. Apply approximately 50 psig of pressure through the line,
and then shut off the valve to keep the pressure suspended in the line. Wait for about two
minutes and monitor the pressure reading to see if it drops. If the valve was shut off at 50
psig and stays at 48 psig for two minutes, the line has no leaks. If the pressure drops
below 48 psig and continues to fall, the line either needs to be replaced or the fittings are
not tight. All four lines to the probe should be checked in this matter before checking the
controller for leaks.
Leak checking the controller requires zero air and a bottle of leak detection solution. Cap
off any potential ports, which will allow pressurized air to escape, for example the
instrument air out. Pressurize the unit with 50 psig and monitor for any leaks with the
leak detection solution at all the fittings (the dilution air regulator has a bleeder valve, so
an air flow sound is normal). If the leak detection solution bubbles at any fittings points,
reconnect or replace the fitting. Once the Model 200L Single Dilution Probe Controller is
leak checked, the controller can be put back into service.