Parr Instrument 4575/76 HP/HT - Manual (Page 9)

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4575/76 HP/HT Pressure Reactors
9
Other Vessel Head Fittings
Safety Rupture Disc
There is a safety rupture disc attached to the head
which is intended to rupture and release the pres-
sure before it reaches a dangerous level. A metal
tag wired to the safety head identifies the burst
pressure at room temperature for that particular
disc. A similar tag is furnished with each replace-
ment disc. This tag must remain with the apparatus
at all times so that both present and future opera-
tors will be aware of the disc rating. Users should
read the discussion of rupture discs given in the
Instruction Manual 231M for a complete description
of the characteristics of rupture discs and the pre-
cautions to be observed when operating pressure
equipment protected by this type of safety device.
A typical pre-bulged disc can be used to 90% of the
rating on the tag. For additional protection, the user
should install an adequate and safe venting system
for removing any toxic, flammable or volatile ma-
terial which would be released if the rupture disc
should burst. A connector for attaching 3/8” OD
tubing to the discharge port of the rupture disc is
provided for this purpose.
Type J Thermocouple
A Type J thermocouple in a 1/8” diameter Stainless
Steel sheath is furnished with the reactor. Insert
this thermocouple into the thermowell, connect the
A470E2 extension wire to both the thermocouple
and the receptacle on the back panel of the control-
ler. For a single thermocouple connect to the "Pri-
mary Temp Input". (If a high temp cut off package
is part of the system a second thermocouple may
be inserted in the thermowell or alternately in the
heater to the vessel wall.)
Pressure Gage
The pressure gage furnished with this reactor has
a T316 Stainless Steel Bourdon tube. Gages are
furnished in a variety of ranges to meet individual
needs. Typically, the gage and the rupture disc are
furnished as matched ranges. For applications
where a gage is selected with a range under 1000
psi, a relief valve is added and set to protect the
gage. A 1000 psi rupture disc is installed as the fail-
safe vessel protection.
For highly corrosive applications where the vapor
phase might corrode the stainless Bourdon tube,
Parr offers isolator assemblies in a variety of materi-
als. These isolators with their internal piston isolate
the vapors from the gage.
The gage adapter includes a ¼” NPT side port with
a plug installed. This position may be used for a
variety of fittings such as a needle valve, pressure
transducer or relief valve.
Gage and Valve Adapters
The pressure gage and the combined gas inlet and
sampling valves are attached to the head with an
adapter which allows these fittings to be drawn up
tightly when facing in any direction. To attach these
fittings to the head, screw the gage or valves firmly
into the adapter, then run the 366HC bushing onto
the threaded stem as far as it will go. Screw this
assembly into the head through the 326HC com-
pression nut until the nose of the adapter is seated;
then back it off until the valve or gage is facing in
the desired direction. Now hold the fitting firmly in
place and close the joint by tightening the 326HC
compression nut. This connection can be made and
broken repeatedly without destroying the sealing
faces. A light coating of thread lubricant, such as
Parr No. 424HC2 High Temperature Anti-Seize Lube,
applied to the threads and to the nose of the adapter
will help to obtain a tight joint.
Note: Do not use Grafoil ® tape on the straight
thread connections of the coned adapters
and mating bushings. Grafoil ® tape should
only be used on the (NPT) threads such as the
needle valves or gage connection. Refer to
instruction manual no. 668M 1358HC Grafoil ®
Tape General Guidelines for use.