Parr Instrument Series 4560 - Manual (Page 11)

Mini Bench Top Reactors
w w w . p a r r i n s t . c o m 11
How to Use the Vessel
Removable Vessels
Always remove removable vessels from the support
stand before attempting to open or close them.
To open the Vessel
Open the gas release valve to discharge any internal
pressure. For the bolted closure, loosen the six cap
screws in the split ring sections. Loosen the cone
pointed screw in the outer band and lower the band
to rest on the table. The ring sections can now be
removed, and the head with all attached fi ttings is
free to be lifted from the cylinder. Handle the head
carefully so as not to damage the stirring shaft and
other internals when they are outside of the cylin-
der.
Before Closing the Vessel
Examine the head gasket or o-ring carefully to be
sure that it is in good condition. After considerable
use, some of the PTFE gasket may extrude into a
thin, ragged edge around the inside and outside
diameters. This does not necessarily mean that the
gasket must be replaced, but the extruded portion
should be removed with a sharp knife. Examine the
mating surfaces on the cylinder and head to be sure
they are clean and free from burrs; then set the head
on the cylinder.
Sealing Vessels with PTFE Gaskets
Initially tighten the cap screws to 15 ft-lbs then
increase to 20-25 ft-lbs. Tightening should proceed
in a criss-cross pattern rather than progressively
around the circle. Let the vessel stand for about fi ve
minutes after the initial tightening; then tighten the
cap screws again. This will compensate for any ten-
dency of the PTFE gasket to fl ow under the loading
pressure.
Sealing with Flexible Graphite Gaskets
Initially tighten the cap screws to 15 ft-lbs then in-
crease to 20-25 ft-lbs. Tightening should proceed in a
criss-cross pattern rather than progressively around
the circle.
Flexible graphite gaskets tend to be somewhat
fl akey. To extend the useful life of these gaskets, fi rst
rough up the sealing surface of the cylinder with
120 grit sand paper to ensure the gasket remains in
the head groove and does not stick to the cylinder.
Secondly, coat both sealing surfaces with a silicone
lubricant. This process will aid in compressing the
gasket so it does not break apart after one use.
Recommended Bolt Torque
PTFE or
Flexible Graphite 0-3000 psig
(0-200 bar) 20-25 ft-lbs
O-ring Closures
The split rings used with an o-ring seal do not in-
clude any compression bolts.
With the easy close split ring, the o-ring is attached
to the pilot on the underside of the head. When
closing the vessel, set the head on the cylinder and
press down on the head until the bottom of the head
meets with the cylinder fl ange. Then install the two
split ring halves and attach the outer drop band.
Note: The following steps are common to both
head confi gurations.
Fixed Head Vessels
Fixed head vessels are opened and closed with the
same procedure used for removable vessels except
that they are opened and closed with the head in
place. Before opening the vessel lower the heater
and swing it well to the side so that it will not be
damaged by any materials that drip from the ves-
sel as it is opened. When closing the vessel always
hold the cylinder until both split ring sections are in
place to lock the cylinder to the head.
Gas Connections
For a gas connection to the vessel, use the A495HC
pressure hose furnished with the reactor. Attach the
hose to a pressure regulator or fl ow control valve on
a commercial gas cylinder using PTFE tape or other
thread sealant on the 1/8” NPT male nipple and on
the 1/4” NPT bushing, if used. Then screw the Type
A coned pressure fi tting into the adapter attached
to the gas inlet valve and tighten the compres-
sion nut fi rmly. Do not use any thread dope or tape
on the coned fi tting. The A495HC pressure hose is
made of reinforced Nylon which can be used for all
non-corrosive gases at pressures up to 2500 psig.
For operations involving corrosive gases, this hose
should be replaced with an A490HC hose (optional)
which has a PTFE lining and a braided stainless steel
outer covering. These hoses have the same fi ttings
as in the A495HC.