Parr Instrument Series 4558 - Manual (Page 22)

4555 - 58 Series
5G & 10L Pressure Reactors
- 21 -
EXPLOSION PROOF OPERATION
If the local safety code requires that equipment installed in the user’s laboratory must be
explosion proof, there are five possible ignition hazards to be considered:
1. The Motor
The standard variable speed motor is not explosion proof, yet these motors are not unduly
hazardous if operated in a well ventilated location where care is taken to prevent the
accumulation of explosive gases or vapors. To eliminate any possible spark hazard originating
at the motor, Parr can furnish an air motor as described above, or the reactor can be equipped
with a variable speed, encased electrical explosion proof motor which is approved for use in
Class 1, Groups C & D, and Class 2, Groups E, F, & G atmospheres. Explosion proof motors
are furnished with a temporary power cord and plug which are not explosion proof. The user
should remove this temporary wiring and replace it with an explosion proof wiring as required to
comply with the local electrical code.
2. The Temperature Controller
The 4848M/A3600HC_Series Temperature Controllers furnished with these reactors contain
switches and other elements which are not explosion proof. The minimal spark hazard
associated with these units can be resolved by installing the controller in a remote location
outside of the hazardous area or by enclosing it in an approved explosion proof housing. If
enclosed within a positive pressure, clean air housing, the discharge from the housing must be
directed into a safe area. If requested, Parr will furnish the long lead wires needed to mount the
controller in a remote location. If the controller is to be installed in an explosion proof housing,
the user must provide the necessary housing and installation.
3. Slave Box Control
Reactors furnished with 3-zone high power heaters are supplied with a slave control box.
These slave boxes also contain switches and other elements that are not explosion proof. The
minimal spark hazard associated with these units can be resolved by installing the controller
and slave box in a remote location outside of the hazardous area or by enclosing it in an
approved explosion proof housing. If enclosed within a positive pressure, clean air housing, the
discharge from the housing must be directed in to a safe area. If requested, Parr will furnish the
long lead wires needed to mount the controller and slave box in a remote location. If the
controller is to be installed in an explosion proof housing, the user must provide the necessary
housing and installation.
4. The Heater
The elements in the heater could be dangerous in an explosive atmosphere if the surface
temperature of the element becomes high enough to ignite flammable vapors. This hazard must
be evaluated for each individual installation since major modifications are required if the heater
must be isolated from the surrounding atmosphere. Users who consider this a significant hazard
are urged to contact Parr Instrument Company for further discussion and suggestions which
might be helpful. Parr is currently offering aluminum block heaters (4555 only) and circulating
jacketed cylinders which have been used in explosive environments.
5. The Wiring
Unless specifically designed for use in hazardous atmospheres, the wiring in these reactors
will not meet the standards prescribed for explosion proof equipment. Optional, intrinsically safe
barriers are available.