Parr Instrument 4575/76 HP/HT - Manual (Page 12)

P a r r I n s t r u m e n t C o m p a n y
4575/76 HP/HT Pressure Reactors
12
How to Use the Vessel
Fixed Head Vessels
First, lower the heater and push it to the side. Be-
fore attempting to remove the split ring open the
gas release valve to discharge any internal pressure.
Raise the cylinder support holder to the bottom of
the cylinder. The head with any attached connection
lines will remain in place.
Moveable Head Vessels
First, open the gas release valve to discharge any
internal pressure. Remove the complete vessel as-
sembly from the support stand.
To open the Vessel
Loosen the bolts in a criss-cross pattern reversing
the tightening procedure, gradually decreasing the
torque on each bolt. The head assembly can be re-
moved from the cylinder. Handle the head carefully
so that no damage will occur to any of the internal
fittings.
Before closing the Vessel
Examine the head seal carefully to be sure that it
is in good condition. The seal should not have any
nicks, be hardened or deformed. Also examine the
mating surfaces on the head and cylinder to be sure
they are clean and free from burrs.
To Close the Vessel
Place the two split ring halves around the head and
cylinder flanges. Close the latches on the fixed head
split ring. Install the drop band on the movable
head split ring.
A torque wrench is furnished with these vessels
and it includes an adapter for the 12 point heads of
the bolts used in these split rings. The amount of
torque to be applied will depend upon the intended
maximum operating pressure. To ensure a good
seal over the full operating range apply the recom-
mended bolt torque per the table below.
Recommended Bolt Torque
Material Pressure (psi) Torque (ft-lb)
PTFE 0 - 3000 35 ft-lbs
Flexible Graphite 0 - 3000 35 ft-lbs
PTFE or Flexible
Graphite
4000 - 5000 40 ft-lbs
Pick a starting bolt and tighten it to approximately
15 ft-lbs. Then by-pass the adjacent bolts and move
around the closure to a bolt approximately 180 de-
grees from the starting bolt. Torque all bolts to the
initial 15 ft-lbs. Then proceed with the same pattern
increasing the torque in 10 ft-lbs increments.
Note: Flexible graphite gaskets tend to be
somewhat flakey. To extend the useful life
of these gaskets, first rough up the sealing
surface of the cylinder with 120 grit sand pa-
per 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.
Gas Connections
Gas connections are dependent on applications.
For most applications the stainless steel hose fur-
nished with the system is sufficient. Attach the Type
“A” coned pressure fitting into the adapter attached
to the gas inlet valve and tighten the compres-
sion nut firmly. Do not use any thread dope on the
coned fitting.
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