HVAC Chemical Filter Units

This article describes the minimum requirements for chemical filter units for use with HVAC systems.

HVAC Chemical Filter Units

HVAC Chemical Filter Units

HVAC Chemical Filter Units


Product Data shall include the following information:

Manufacturer’s technical product data for each unit showing dimensions, weights, capacities, ratings, fan performance with operating point clearly indicated, motor electrical characteristics, electrical power requirements, starters, controls, finishes of materials, and installation instructions.

Shop Drawings shall show the following information:

a. Unit dimensions, weight loading, required clearances, field connection details, and methods of suppor

b. Wiring diagrams indicating power, signal and control wiring. Wiring diagrams shall differentiate between manufacturer installed and field installed wiring.

Maintenance Data shall include the following information:

a. Maintenance instructions, including instructions for lubrication, filter replacement, motor and drive replacement, and spare parts lists.

b. Product data, shop drawings, spare parts list, and wiring diagrams in operating and maintenance manuals, in accordance with requirements of Manufacturer’s instruction.

Quality Assurance

Electrical components, devices, and accessories shall be listed and labeled as defined in NFPA 70, Article 100, by a testing agency acceptable to authorities having jurisdiction, and marked for intended use.

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Fan Section

  • Fan shall be of industrial quality, heavy duty, with aluminum wheel and housing and shall be AMCA type C construction.
  • Fan shall provide the specified air flow at specified external static pressure with a dirty filter allowanc The fan selected shall operate a minimum of 15 percent capacity from the surge line at the minimum design flow.
  • Fan bearings shall be pillow block, self-aligning, lubricated bearings with grease lines extending to outside of the unit or pre-lubricated, sealed, non filling slot, high load, anti-friction ball bearings with a minimum L-10 life of 25,000 hours.
  • Fan shafts shall be solid steel, turned, ground and polished.
  • Fan wheels shall be keyed to the shaft and designed for continuous operation at the maximum rated speed and motor horsepower.
  • Fan wheels and shafts shall be statically and dynamically balanced individually, and as an assembly. Fan selection shall be made near the midpoint of the fan curve and selected to operate at least 20 percent below the first critical sp
  • Fan shall be selected for normal operation within 10 percent of the best efficiency poi Fans shall be selected within the middle range of the fan airflow versus head application curves.
  • Fans shall be mounted on unitary base with spring vibration isolators. Fan, motor, drive belts, unitary base and spring isolators shall be furnished as a complete unit.
  • The fan assembly shall be internally isolated on spring mounts. Vibration isolation mounts shall isolate 90 percent of fan and motor vibration.


  • The industrial front access housing shall be constructed of 16 gauge minimum galvanized steel, continuously welded, reinforced with vertical formed channel supports at 24 inches intervals.
  • Housing shall be provided with gasketed front access doors.
  • Latches shall have a positive locking action and shall include a stainless steel shaft.
  • Hinges, locks and latches shall be constructed of stainless steel.
  • The housing shall be provided with lifting lugs and structural shape skids or supports.
  • The housing shall be designed to facilitate fan and motor maintenance and removal.
  • Door seals shall be attached by mechanical means and designed for replacement. Seals shall not be glued on except in conjunction with mechanical attachment.
  • Door closures shall be of the hinged bulkhead type where the rear seal nearest the hinges shall not be compressed completely prior to latching the door. Banjo hinges shall not be used.
  • Intake and discharge of unit shall be suitable for ductwork connection.
  • Fasteners shall galvanized steel including motor hold down bolts. Set screws and general hubs shall be coated prior to assembly with an anti-seizing compound. Slotted screws shall not be used.
  • Housing shall be painted inside and out with manufacturers standard coating before assembly. Project requirement or equipment location may require additional corrosion resistant coatings.


Static pressure drop shall be 872 Pa maximum including outside air louvers, dampers, media, pre and final filters and dirty filter allowance.

Media section shall contain a minimum of two beds.

Type and quantity of media shall be selected to provide an ISA G1 environment inside the protected space and shall be based on the air quality at the project or protected space location.

Electrical and Motors

  • Internal wiring shall be color coded and tagged with permanent shrink tube labels at each termination, junction box, and devic Wire label designations and color coding shall correspond to the schematic and wiring diagrams furnished with the unit.
  • Wiring shall be copper and connections shall be lugged bolted typ Wire nut connections shall not be acceptable. Connections shall include lock washers and anti-Galvanic corrosion protection joint compound to ensure long term integrity.
  • Conduit entrance plates of sufficient dimensions shall be provided for external wiring conduit connection and entrance (side or/and bottom).
  • Electrical components such as motors, controllers, contractors, and non-fused disconnects shall be provided for complete and operable system Interconnecting wiring for components of packaged equipment shall be provided as an integral part of the equipment. Starters shall be suitable for hand/off/auto functions.
  • Fan shall be provided with independent power and control circuit.
  • Externally mounted unit terminal box shall be utilized for connection between the unit and remote mounted control panel. Power and control wiring shall be wired to the terminal box. Terminal strips shall be provided as needed and each strip point shall be clearly labeled for easy field connection.
  • Current sensors shall be provided between starters and motors and wired to terminal strip in the terminal box for fan failure alarm and fan monitoring.
  • Controls, motors and power enclosures shall be for the electrical classification in which the unit is located.


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