Parr Instrument Series 5500 - Manual (Page 10)

Compact Micro Reactors
P a r r I n s t r u m e n t C o m p a n y 10
How To Use The Vessel
Removable Head Vessel Flat Gasket Closure
Always remove the vessel from the heater before at-
tempting 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 re-
moved, and the head with all attached fittings is free to
be lifted from the cylinder. Handle the head carefully
so as not to damage the stirring shaft and other inter-
nals when they are outside of the cylinder.
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 re-
moved with a sharp knife. Examine the mating surfac-
es on the cylinder and head to be sure they are clean
and free from burrs; then set the head on the cylinder.
To Close the Vessel
Slide the two ring sections into place and position
them so that the shallow socket drilled in the outer
surface of one of the ring sections is 180º from the
gage face. Raise the outer band into place around the
ring sections and position the band so that the cone
pointed screw enters the socket described above; then
tighten the screw lightly to hold the band in place.
Sealing Vessels with PTFE Gaskets
Tighten each of the cap screws with the wrench fur-
nished with the apparatus. Apply a firm but hard pull
to each screw. If a torque wrench is available, apply 15
ft-lbs to each screw. DO NOT apply more than 25 ft-lbs
of torque to these bolts as this can deform the head of
the reactor. Tightening should proceed in a criss-cross
pattern rather than progressively around the circle. Let
the vessel stand for about five minutes after the initial
tightening; then tighten the cap screws again. This will
compensate for any tendency of the PTFE gasket to
flow under the loading pressure.
Routinely inspect cap screws on the split ring closure
for lubrication and cleanliness. It is important to clean
and lubricate them periodically so that the required
torque is achieved when tightening the bolts.
O-Ring Closures
The split rings used with an O-ring seal do not include
any compression bolts.
With the easy close split ring the O-ring is attached to
the pilot on the underside of the head. When clos-
ing the vessel, set the head on the cylinder and press
down on the head until the bottom of the head meets
with the cylinder flange. Then install the two split ring
halves and attach the outer drop band.
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 flow 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 fitting into the adapter attached to the
gas inlet valve and tighten the compression nut firmly.
Do not use any thread dope or tape on the coned fit-
ting. 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 fittings as in the A495HC.
Pressurizing the Vessel
Check all valves carefully before admitting gas into the
system. The liquid sampling valve must remain closed
throughout the charging procedure. The gas release
valve must also be closed unless the vessel is to be
purged, or unless there is to be a continuous flow
through the reactor during a run. Always make certain
that the pressure in the gas tank is greater than the
pressure in the vessel; otherwise liquid will be forced
out of the vessel and into the gas tank when the inlet
valve is opened. If there is any possibility that the tank
pressure might not be high enough to force gas into
the reactor, install a one way check valve (optional) in
the gas line to prevent any reverse flow.
With the inlet valve open and the flow control valve on
the gas tank closed, open the main valve on the gas
tank only about one-quarter turn; then use the flow
control valve or the valve on a pressure regulator to
control the flow of gas into the vessel. After the de-
sired pressure has been reached, close the tank valves
and the vessel inlet valve and disconnect the hose at
the vessel end.