Ludlum Measurements 3100, Manual, Page: 52 / 57

A-6
d.
Carefully slide the gas cylinder and regulator into the gas cylinder holder on the calibrator base plate. It
may be necessary to loosen the cylinder-locking screw. Line up the outlet valve connector with its
mating fitting on the calibrator base plate. Remove and discard the three caps on the base plate tubing.
e.
Hand-tighten the outlet valve connector. Tighten the cylinder-locking screw and finish tightening the
outlet valve connecter with a wrench.
f.
Connect the two lengths of plastic tubing supplied to the inlet and outlet of the calibrator.
A.2.4 Leak Check.
a. Close metering outlet valve and open both metering inlet valve and regulator outlet valve.
b. Apply pressure to regulator by opening lecture bottle valve.
c.
Adjust pressure by slowly turning the outlet pressure adjust knob clockwise to approximately 15 PSIG
on the outlet pressure gauge.
d.
Close the lecture bottle valve to isolate tubing from the gas supply. If the system is leaking, the
cylinder pressure gauge will slowly drop.
e.
A tight system should lose less than 50 psi on the cylinder pressure gauge in one hour.
f.
If tubing is leaking, determine whether the leak is in the regulator part or in the metering volume and
associated valves.
g.
Having determined the portion which is leaking, tighten appropriate connections and retest.
Note: The calibrator is a precision instrument capable of accurate, reproducible results. Operation is simple, but
erroneous results can be obtained if an incorrect technique is used. Before proceeding further, note that the bellows-
sealed valves on either side of the metering volume have Teflon seals, which close with a small amount of pressure.
CAUTION
The valves may be damaged by the use of excess pressure when closing them.
Note: Before injecting tritium gas into the instrument’s chamber, air must be flushed from the calibrator.
A.2.5 Initial Procedure.
The procedure need only be done the first time the cylinder is connecting to the regulator.
a. Open the lecture bottle valve momentarily, reclosing tightly.
b. Open the metering outlet and inlet valves, as well as the regulator outlet valve. Turn the regulator
outlet pressure adjust knob clockwise until the cylinder pressure gauge drops to 0.
c.
Close the metering inlet and outlet valves and back off the outlet pressure adjust knob.
A.2.6 Flushing.
The metering volume should always be flushed before performing a calibration.
a. Check to see if the metering inlet and outlet valves are closed, the regulator outlet valve is open, and
the outlet pressure adjust knob is backed off counterclockwise until it is loose.
b. Momentarily open and reclose the lecture bottle valve, admitting as to the regulator and causing the
cylinder pressure gauge to indicate.
c.
Turn the outlet pressure adjust knob clockwise until the outlet pressure gauge reads about 20 psi.