Page 2 - BEST-Type-Y-&-Z-Unit-Technical-Bulletins

Product Description Model YZ101A

Model YZ101A is a Type Y or Z pressurization unit designed to Type Y & Z
protect electrical equipment in Class I and Class II Hazardous
Areas. When connected to a supply of protective gas, the Model Pressurization Unit
YZ101A will supply, regulate and monitor the protective gas
supply to a protected electrical enclosure. Type Z applications
reduce the hazardous area rating inside the enclosure from Class I Applications Class II Applications
Division 2 / Zone 2 to Unclassified. This allows general purpose
equipment to operate in Division 2 / Zone 2 areas. Type Y Up To 2 Cubic Feet Up to 10 Cubic Feet
applications reduce the hazardous area rating inside the
enclosure from Division 1 / Zone 1 to Division 2 / Zone 2. This
allows Division 2 / Zone 2 equipment to operate in Division 1 Technical Bulletin YZ101A TB-R0 © 07.23.2018
/ Zone 1 Hazardous Areas.
Unit Operation

Prior to Start-Up: Ensure Protected Enclosure Power
is OFF, Enclosure Pressure Control Regulator is closed,
Protective Gas Supply is ON and alarm system is
activated (if utilized). If utilized, test Purge Vent for proper
operation. Class II Area Start-Up: Remove all dust
from protected enclosure. Close and seal Protected
Enclosure. Open Enclosure Pressure Control Regulator until
a “Safe” reading is shown on the Enclosure Pressure Gauge.
Class I Area Start-Up: Close and seal Protected Enclosure.
Open Enclosure Pressure Control Regulator until a “Safe”
reading is shown on the Enclosure Pressure Gauge. Allow unit
to purge protected enclosure for the required time marked on
Unit Start Up Instructions or for 5 minutes, minimum. Confirm
protected enclosure “Safe” pressure is stable. Energize
protected enclosure equipment. Loss of “Safe” pressure
requires immediate attention. Protected enclosure power
should be de-energized if “Safe” pressure cannot be restored
within a reasonable amount of time.

Unit Specifications

Class I & II Maximum Enclosure Volumes: 2 &10 cubic feet
Universal Unit Weight: 3.5 lbs. Universal Mount Unit
Vertical & Horizontal Unit Weights: 8.0 & 8.0 lbs. less Pressure Switch for
Operating Temp. Range: -20° F - 120° F any side or panel mounting
Protective Gas Supply: * Air or Inert Gas
Supply Pressure w/ RR-4 Regulator: 5 psi maximum
Supply Pressure w/ PV-2 Vent: 80 - 125 psi maximum
Unit Supply Connection: 1/4” tube fitting
Enclosure Supply: 1/4” tube fitting
Enclosure Reference: 1/4” tube fitting
Safe Enclosure Pressure: 0.25” w.c.
Safe Pressure Flow Rate: ** 0.1 - 3.5 SCFH per cubic foot
Switch Set Point on Decrease: 0.15” w.c. ± 0.02”
Pressure Switch Conduit Port: 1/2” FPT
Pressure Switch Contact Ratings: See EPSK Bulletin
* Air must contain no more than trace amounts of flammable vapors.
** Enclosure integrity determines safe pressure flow rate.
Recommended Accessories

Redundant safety devices are necessary to protect the enclosure
from excessive pressure of the protective gas supply in accordance
with the requirements of NFPA 496, EN 50016 and IEC 60079-02. Vertical Mount Unit
Best Purging Systems Corporation therefore strongly recommends with Pressure Switch for
a Model RR-4 Redundant Regulator installed upstream of this unit’s left or right side mounting
enclosure pressure control regulator. As an alternative, a Model Horizontal Mount Unit
PV-2 Spark Arresting Purge Vent may be installed on the protected
enclosure or the last enclosure of a pressurized enclosure array to with Pressure Switch for
relieve excessive pressure created by other sources. top or bottom side mounting

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