Parr Instrument 1108 - Manual (Page 13)

1108 Oxygen Combustion Vessel
w w w . p a r r i n s t . c o m 13
1. Assemble the bomb with the head in the cyl-
inder and count the number of turns required
to bring the screw cap down firmly against the
head.
2. Then open the bomb; remove the head and
replace the screw cap, but turn it down to only
one-half of the turns previously counted. This
will usually be about four turns.
3. With the screw cap in this position, use a dial
gage to measure the vertical deflection when
lifting the screw cap upward. If this measure-
ment exceeds 1/32 inch (0.030”), the screw cap is
unsafe and should be discarded.
4. The cylinder can then be returned to the fac-
tory for inspection. If the threads on the cylinder
are in good condition, a new screw cap can be
custom-fitted to the cylinder.
Never under any circumstances use oil on the O-
rings which seals the bomb head or on any of the
valves or fittings which handle compressed oxygen.
This precaution applies to all of the oxygen bomb
parts to the oxygen filling connection as well.
Although Parr oxygen combustion vessels are made
from alloys which will withstand most corrosive
gases, these bombs will not resist chlorine, fluorine
or bromine in the presence of moisture. If samples
yielding appreciable amounts of these elements are
burned in a Parr vessel, the interior surfaces may
become etched or corroded. In such cases the bomb
should be emptied and washed as quickly as pos-
sible after each combustion.
If the interior of the bomb should become etched
as mentioned above, the resistance of the metal
to further attack can be improved by restoring the
surface to its original highly polished condition.
Bombs needing repolishing or other repair work can
be returned to the factory. A periodic overhaul and
test at the factory will help to keep any Parr oxygen
combustion vessel in first-class condition.
See page 14 for a Maintenance Checklist.
Bomb Repairs and Proof Tests
The 20VB valve seat, 230A, 415A, and the four 238A
O-rings should be replaced after every 500 firings,
or every six months, whichever occurs first. If the
bomb is used for samples containing chlorine, these
repairs should be made after every 250 firings. Parr
oxygen combustion vessels can be returned at any
time for repair and testing. A factory test is recom-
mended after every 5000 firings, or after any of the
following conditions; (a) fired with an excessive
charge, (b) ignition of any internal components,
(c) machined by any source other than the factory,
(d) damaged by corrosive vapors that might have
exceeded 80% of the corrosion allowance, or (e) any
changes in the threads on the bomb cylinder and/or
screw cap.
When returning a oxygen combustion vessel to the
factory, ship it to:
Parr Instrument Company
Attn: Repair Department
211- 53rd Street
Moline, Illinois 61265
A purchase order covering the repair work should be
included with the shipment or mailed to the same
address as no repairs will be started without specific
instructions. Be sure to include a return shipping
address and the name and telephone number of the
individual to be contacted if questions arise con-
cerning excessive repair costs or other problems.
Individual repair parts can be ordered from any Parr
dealer or direct from the factory.