howorth exflow 28 prevents airborne infection … · a critical factor governing the performance of...

Exflow 28 – Technical Specification

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HOWORTH EXFLOW 28

PREVENTS AIRBORNE INFECTION

TECHNICAL SPECIFICATION

Exflow 28 – Technical Specification Rev 01

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TECHNICAL SUMMARY

Terminal Unit size 12’-3 ¼” x 12’-3 ¼” x 23 ¾”

Terminal Unit weight 3527 lb

Clean filtered area 9’-2 ¼” x 9’-2 ¼”

Partial walls finish 78 ¾”

Minimum distance from Operating Room wall to clean zone

39 ½”

Height to diffuser screen 8’-6” x 9’-6”

Electrical requirements Absorbed power 20 amp three phase 460v - 60Hz Note: When optional extras are fitted i.e. Operating Lamp, power requirements increase from 20 amp to 25 amp.

UCV Heat Gain 11950 BTU/hr (3.5 Kw) (Operational)

Noise level 55dBA dependent on background noise level

Standards unmanned HTM 03-01

Supply air volume from terminal 6357 CFM (Larger Volume flow rate available on request)

Recirc air volume 3920 – 4768 CFM

Fresh air volume

1589 – 2436 CFM (To suit operating room heat gains) (100% Fresh Air System available on request).


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Air change rates within the clean zone Approx 500 per hour

Drawing No. EX 90/148 Rev H

PERFORMANCE

DISCHARGE AIR VELOCITY.

Measured 78 ¾” from F.F.L. will be 75 FPM average within the discharge area 9’-2 ¼” x 9’-2 ¼” in accordance with HTM 03-01. Measured 39 3/8” from F.F.L. will be not less than 39 FPM within the central operating zone 5’-10 7/8” x 5’-10 7/8” in accordance with HTM 03-01. A critical factor governing the performance of the Exflow and its discharged air velocities is the provision of the required primary air input from the air conditioning system. The fresh air input volume requirement for the Exflow U.C.V. system is in the order of 742 CFM, for the purging of pollutants. However, to ensure satisfactory climatic control within the operating room a volume of 1589 – 2486 CFM should be provided subject to local conditions. A further factor affecting the Exflow airflow pattern is the temperature differential between the supply air and the room air. The supply air temperature should not exceed room temperature i.e. room air temperature measured in the return air duct. Optimum performance will be achieved when the supply air is maintained at 1°C below the room air temperature. Bacteria levels within the Ultra Clean zone shall not exceed the maximum levels as recognised by international infection control guidelines as follows. Bacteria shall be measured as evidenced by the presence of Colony Forming Units (CFU). Average within 11’ 7/8” of wound site less than 10 CFU per 35.3 cubic feet of air. Average in the remainder of the clean zone, less than 20 CFU per 35.3 cubic feet of air.


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STANDARDS

The Exflow U.C.V. system complies with the following standards. HTM 03-01 2007 ventilation in healthcare premises. All classifications are given as the minimum standards achieved in the unmanned state.


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GENERAL SPECIFICATION The Integral Exflow has four fans housed within the canopy corner sections each with sound attenuation to all air inlets and outlets. As a result of being self-contained NO additional space is required in the hospital plant room to accommodate fan units. This model is therefore the most economical for retro-fitting to upgrade an existing operating room or where space is otherwise limited. The overall dimensions of the unit are 12’-3¼” x 12’-3¼” x 23¾” deep and the unit can be surface mounted or almost totally recessed into the ceiling void (21½” max.). Fan units are double inlet with built-in, external rotor motor, speed variable via VFD (Variable Frequency Drive). Primary or pre-filtration of the recirculated air from the room is by G3 / EN779 filters. The pre-filters are located within the return air grilles on the underside face of the canopy and are easy to replace. Final filtration is by 8 HEPA (high efficiency particulate air) filters having an efficiency of 99.995% MPPS (Most Penetrating Particle Size) H14/EN1822. These filters are fitted in the ceiling of the 9’-2 ¼” zone. A magnehelic pressure differential gauge is fitted to the Exflow unit to monitor HEPA filter soiling. Clear acrylic partial walls 0.39” thick extend down from the underside of the canopy and terminate 78¾” from finished floor level. Discharge area within the clear partial walls size 9’-2½” x 9’-2½”. Mounting frame height will be between 9’-7¼” and 11’ 7/8” from F.F.L. The Exflow and any associated optional equipment are powered from a separate cabinet containing all circuit breakers, terminals, contactors, relays, VFD’s, etc., with door mounted system malfunction warning lights; surface mounted to the wall in the plantroom or other non-sterile most convenient place within 50 ft of the operating room. Controls include individual VFD’s, one per fan, (4 fans), individual fan fail warning lights and dirty filter indicator. Size of basic panel: 1’-11 5/8” Wide x 2’7 ½” High x 1’ Deep. Note: When optional extras are fitted as referred to in Technical Summary, panel aspect size increases to 2’7 ½” Wide x 2’7 ½” High x 1’ Deep.


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Exflow theatre control panel (24 volt) will be suitable for being flush mounted into a prepared opening 1’-1¾” (High) x 1’-1¾” (Wide) x 3 1/8” (Deep) in the operating theatre wall. This displays the standard user controls for the Exflow, i.e. standby/operational mode switches, emergency stop switch, system fault warning indicator, Exflow perimeter light switch and a lamp test switch. Perimeter lighting is by 8 integral luminaires recessed into the Exflow return air grille panels each containing 2 x 4 ft colour corrected K4000 fluorescent lamps controlled by high frequency ballasts to provide a minimum lighting level of 92.9 ft/candles within the ultra clean zone 39 3/8” from F.F.L. Graded air diffusers, produced as 4 single sheet perforate panels, suspended directly below the terminal HEPA filters are secured by quick - release catches. The panels are easily removed to facilitate changing of HEPA filters. The exclusive design of this diffuser is material in creating the concentrically graded airflow profile. Construction - The Exflow unit is constructed from welded, zintec steel sheet in 4 separate sections to fit round the operating light stem. The 4 sections are bolted together and to a 4” x 2” RSC mounting frame on site. This is either supported on drop rods or bolted directly to the slab/steelwork. Finish - Polyester powder coated. Standard colour RAL 9010 textured 20% gloss. Fresh Air Inlets are provided into the fan mixing chambers for the introduction of climatic controlled air. These can be located on the top or into the sides of the fan sections as required to suit space limitations. Howorth Air Technology reserves the right to change the product specifications and design without prior notice.


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OPTIONAL EXTRA FEATURES OPERATING LAMPS Howorth Air Technology should always be consulted before selection of an operating lamp to ensure compatibility and optimisation of the airflow. Controls for the operating lamp can be incorporated in the Exflow theatre control panel with associated transformers, relays, emergency battery changeover switch, etc. located in the Exflow power distribution cabinet. Early selection of the operating lamp is essential to ensure that its mounting stem can be provided to the correct length and installed prior to the Exflow 1st fix.

howorth exflow 28 prevents airborne infection … · a critical factor governing the performance of...

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