York R-407C Air Filtering System, AIR INLET SYSTEM General, Refrigeration System, Compressors

FORM 100.50-EG1

All fan motor drives shall be selected for a minimum service factor of 1.2 and have fixed pitched sheaves.

AIR FILTERING SYSTEM

All filter holding frames shall be of heavy-duty construc- tion designed for industrial applications. All filters shall be either side accessible via access doors on both sides of the filter section.

All filter media shall be Class II listed under UL Stan- dard 900. Filter efficiencies shall be rated in accordance with ASHRAE Standard 52-76

Two-inch throwaway filters in an angled filter rack shall be standard. On units with rigid filters, two-inch prefilters shall be installed upstream of the rigid filters.

AIR INLET SYSTEM

General

A factory installed outside air rain hood permanently attached to the cabinet to prevent windblown precipita- tion from entering the unit shall cover inlet openings. The rain hoods on the sides of the unit shall be rotated into the cabinet and secured for shipment so that upon installation they need only be rotated upwards and screwed into place. The outside air hood shall contain a removable and cleanable filter.

All damper assemblies shall be of low leak design. Damper blades shall be fabricated from a minimum of 16 gauge galvanized steel.

REFRIGERATION SYSTEM

Units shall have four compressors for maximum load- matching capability. Each refrigerant circuit shall be controlled with a thermal expansion valve for maximum control at low load conditions.

Evaporator Coils

Evaporator coils shall be direct expansion. Coil tubes shall be 3/8” OD copper, with internally enhanced tubes. Fins shall be enhanced aluminum mechanically ex- panded to bond with the copper tubes. Coil casing shall be fabricated from heavy gauge galvanized steel.

Astainless steel double-sloped drain pan shall be pro- vided under the entire width of the evaporator coil, in- cluding all return bends. The main drain pan shall be sloped a total of 1/4” per foot towards the drainage point according to ASHRAE 62 guidelines. Main drain pan shall be accessible and cleanable in the field. The con-

densate drain opening shall be flush with the bottom of the drain pan to allow complete drainage. Coils in ex- cess of 48” high shall have an intermediate drain pan, extending the entire width of the coil to provide better water drainage.

Compressors

Compressors shall be hermetic, scroll-type, including tip seals to provide efficient axial sealing while prevent- ing scroll tip to base contact, controlled orbit design for radial sealing to incorporate minimum flank-to-flank con- tact for long service life, refrigerant cooled motors, large suction side free volume and oil sump to provide liquid handling capability, annular discharge check valve and reverse vent assembly to provide low pressure drop, silent shutdown and reverse rotation protection, initial oil charge, oil level sight glass, vibration isolator mounts for compressors, and brazed-type connections for fully hermetic refrigerant circuits.

Condenser Coils

Condenser coils shall have 3/8” seamless copper tubes, arranged in staggered rows, mechanically expanded into aluminum fins. Coils shall be protected from hail dam- age with a “V” configuration, with individual flat coils ro- tated from the vertical plane for each condensing circuit.

Condenser Fans and Motors

Condenser fans shall be direct drive, propeller type, discharging vertically. Condenser fan motors shall be 3-phase, totally enclosed air over (TEAO). Thermal overload protection shall be provided for each con- denser fan motor.

Refrigerant Piping

All interconnecting piping between refrigeration com- ponents shall be copper tubing with brazed joints.

Each refrigerant circuit shall be equipped with liquid line filter drier, and moisture indicating sight glass. Each circuit shall also have both high and low pressure switches installed on either side of the compressor and include access fittings for replacement of the pressure switches without removing charge.

Polyurethane sleeves shall protect all small diameter distributor tubing to the evaporator coil to prevent the tubes from copper-to-copper contact during shipment or operation.

POWER SUPPLY

Unit power supply shall be 460V 3-phase 60Hz (208, 230 and 575V optional) single-point power connections with terminal block connections.

YORK INTERNATIONAL 39