Important Notes About Explosion Proof Door Operators

IMPORTANT READ BELOW FIRST

Certain Horton automatic door operators might be used in Nema Class I, Class II or Class III areas, but special considerations must be made.  The chart below should provide a quick guideline.  Please consult a qualified electrical engineer and/or consultant, prior to specifying a door operator system in hazardous areas.  Failure to consult a qualified electrical engineer could result in death, injury or property loss.  Eastern Door Service is providing this information, as a convenient guideline and it is not guaranteed to be accurate.  Eastern Door Service and its employees are not qualified electrical engineers or consultants.

IMPORTANT READ ABOVE FIRST

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 NEMA Classification    Notes and Considerations
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Notes:

  1. You may not need to use explosion proof operators or special equipment if it is completely installed in a corridor or room located opposite a hazardous area (safe side of door opening).  The corridor must be a safe area and have a greater atmospheric pressure than the hazardous area.  Make sure sliding door hold-open beams are installed on the safe side of the door opening.
  2. Switches located inside a hazardous area must be intrinsically safe for Class I areas or sealed for Class II areas.   Intrinsically safe wiring must be ran in a separate conduit.  Do not make parallel switch connections within a hazardous area.  All parallel electrical connections must be made within the safe area or within a purged enclosure.
  3. You might be permitted to use electro-mechanical door operators within a Class II area, provided the motor is sealed and not ventilated.  Switches must be dust tight or intrinsically safe.  Horton Automatics uses a non-ventilated motor, which Eastern Door vulcanizes to ensure a dust tight condition.  This is not a NEMA 4 or 12 motor, but is usually accepted by the local governing authority and your consulting electrical engineer.
  4. Powered switching devices such as motion sensors and presence detectors might be acceptable in Class II Division II areas, provided the devices are rendered dust tight.  The governing authority must approve the use of any such devices.
  5. Always use explosion proof pneumatic or explosion proof electro-pneumatic operators in all Class I areas.  Horton Automatics manufactures pneumatic operators for sliding and swinging doors.  Please contact us for specific details.

 

NEMA CLASSIFICATION

OPERATOR REQUIREMENTS

Class I
Flammable vapors or gases might be present in the room's atmosphere.

Division 1
The condition exists continuously or periodically.

Division 2
The condition exists in the advent of an accident or abnormal condition.

Group A
Acetylene may be present.

Group B
Hydrogen may be present.

Group C
Ethyl-ether, ethlsoe or cyclo-propane may be present.

Group D
Gasoline, lacquer, benzene, butane, hexane, naphtha, propane, alcohol, acetone, benzyl, or natural gas may be present.

Pneumatic Explosion Proof Operator:
Door operator must be all pneumatic or electro-pneumatic with electronic controls and valves mounted in safe area within 50 feet of the door operator location.   Electronic controls and valves might also be mounted within a purged enclosure box if no safe area is within 50 feet of the door.  (Bebco Industries Type Z enclosure for division 2 and Type Y enclosure for division 1)

Switching and Actuation:
Intrinsically safe non-powered contacts (dry contact switching) must be used.   Powered switching devices such as motion sensors or infra-red photo beams may not be used.  All dry contact switches are wired to an extremely low voltage low amperage remote mounted relay module, which are installed in a safe area or purged enclosure.   All switching is done through this module.  One module is required for each switching function; i.e. one for actuation control(s) and one for safety control(s).   A module is not required for each switch, but all switches must have a separate pair of wires pulled to each switch location.  Never parallel wire or daisy chain wires within a hazardous area.

Class II
Combustible dust might be present in the room's atmosphere.

Division 1
The condition exists continuously or periodically.

Division 2
The condition exists in the advent of an accident or abnormal condition.

Group E
Metal dust from aluminum, magnesium, or their alloys, as well as other hazardous metals may be present.

Group F
Carbon black (lamp black), coal or coke dust may be present.

Group G
Flour or other grain dust may be present.

Door Operator:
Pneumatic or explosion proof door operators are not required, but will meet requirements for Class II areas.  Electromechanical door operators must have a NEMA 4 or NEMA 12.  In most conditions a sealed and non-ventilated motor is acceptable, but should be approved by local code officials.  Operator limit switches must be sealed or intrinsically safe.  Rubber boot or seal must be used where the output shaft protrudes through the operator cover.  The control box and electronics must be installed in a NEMA 4 or NEMA 12 enclosure box.  Sloped operator covers should be used to prevent dust build-up.

Door operators can open a door, when mounted on either side of a wall.  The simplest means to automate doors safely in a Class II area, would be to mount them on the safe side of the door opening, if such a condition exists.  Actuation switches in the Class II area would still need to comply with conditions described above.

Switching and Actuation:
Intrinsically safe, waterproof switches or air tight switches are all acceptable.   Powered switching such as motion or presence sensors is sometimes permissible (check with local officials and electrical engineer), but must be sealed in a dust tight enclosure.

Class III
Ignitable fibers might be present in the rooms atmosphere.
Use equipment as described above for NEMA Class II areas.
 

EXPLOSION PROOF DOOR OPERATORS

Series 1000EXP Horton series 1000EXP pneumatic sliding door operator systems are used for light industrial applications and clean room entrances, where NEMA classification requires an explosion proof or dust proof door operator system. Acceptable for use in Class 1, Division 1 or 2, Groups A, B or C and Class 2, Division 1 or 2, Groups D, E, F or G areas.
Series 6-1000EXP Horton series 6-1000EXP  pneumatic sliding door operator systems are used for heavy industrial applications.  Acceptable for use in Class 1, Division 1 or 2, Groups A, B or C and Class 2, Division 1 or 2, Groups D, E, F or G areas.
Series 5000EXP Horton series 5000EXP pneumatic swing door operator systems.  Can be used in conjunction with Von Duprin exit devices with pneumatic latch retraction.  Acceptable for use in Class 1, Division 1 or 2, Groups A, B or C and Class 2, Division 1 or 2, Groups D, E, F or G areas.

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Page last updated Monday, August 20, 2012
by Charles F. Vetter