FW Series Humidity Chambers

The Bemco FW Series of mechanically cooled Glass Door Humidity Chambers have a a temperature range of -28 C to +177 C (-20 F to 350 F) or -73 C to +177 C (-100 F to 350 F) and a humidity range of up to 5% RH to 95% RH (see the Chart below).

These chambers feature direct dry air injection and direct humidity sensors. They operate without dewpoint limit from 5% RH to 95% RH over the range of 30 C to 85 C and even allow operation at 20% RH at 5 C and 50% RH at -14 C!

Based on the F Series of Temperature Chambers, these chambers provide a reliable very low and very high humidity testing platform with a compact floor footprint. Both the narrow and wide range models are housed in the same package.

For "Code D," above, Exterior Height, add approximately 10 inches near the rear of the workspace for fan motors on the FW27 and FW64. All standard systems except the FW64 have air cooled condensing on the refrigeration systems. FW64 chambers have water cooled refrigeration systems.

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Conditioning

Chamber air is recirculated by a high volume, stainless steel axial fan discharging through a hinged rear mounted diffuser baffle to create a uniform environment around your test objects.

The fan is driven by a vertically mounted motor with dual ball bearing races, connected by a large diameter extended stainless steel shaft.

A proportionally controlled single compressor refrigeration system cools the workspace on the Narrow Range System (FWN) and a cascade two compressor system (one refrigeration system cools another) cools the workspace on the Wide Range System (FW). Both types of refrigeration systems utilize modern environmentally friendly refrigerants. The systems include automatic hot gas bypass and suction cooling unloading.

Fast-response open type heaters, located behind a radiation baffle, raise chamber temperature as required.

Chamber humidity is increased by a Bemco mass transfer vapor generator with a sight glass, a low water cutoff, and automatic drain freeze protection. The vapor generator can be shutoff and drained when very low humidity control is desired.

Chamber humidity is decreased by the direct injection of -73 C (-100 F) dew point dry air produced by a dual bed regenerative compressed air drier furnished with an isolation valve, an inlet particulate and coalescing filter, and an outlet filter regulator.

Water and air connections are located at the rear of the chamber.

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Safety Systems and Electrical Wiring

All systems have thermal and current sensors on the compressor, charging valves, and a sight glass as well as numerous safety and reliability protection systems for dependable operation. All electrical wiring meets the United States National Electric Code. UL and CSA approved components are used where possible.

An FW64 right side view is shown in the illustration. Notice the two extra optional access ports on the chamber right side, the overhanging front door to allow flush cart loading and the controls mounted on the side to limit the possibility of water dripping on them when the door is opened. Because the photo is small, you can not quite see the standard door drip trough located directly beneath the chamber door.

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Construction

The FW Series includes a continuously heliarc welded 304 Series stainless steel liner with high temperature fiberglass insulation. No asbestos is used in chamber construction. The outer case is fabricated from cold rolled steel finished in Bemco Blue.

The FW Series also includes:

• A sloped roof insert to minimize potential water dripping on test objects and to meet Mil-Std 810 and Mil-Std 202. This feature reduces overall height (shown in the table above) by 1-1/2 inches.
• A trapped drain line to remove condensed water from the workspace.
• A door drip trough to catch condensed water.

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Controls

The FW Series is furnished with a two channel, microprocessor based, programmable 1/4-DIN, solid state, 256-step ramping controller which includes a 4-line LCD interface display, and a large red LED display.

Temperature inside the chamber is sensed by a precision thermocouple.

Humidity is sensed by a direct reading electronic humidity sensor accurate to + or - 2% RH over the dew point temperature range of -20 C to 85 C (-4 F to 185 F). This sensor is mounted through a sleeve located on the roof near the left side of the door.

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Performance

On Narrow Range Chambers (N), cooling rate from 23 C (+73 F) to -35 C (-31 F) is approximately 45 minutes, or 2 C (3.6 F) / minute. Average heating rate from 23 C (+73 F) to +177 C (350 F) is 3.4 C (6.2 F) / minute, both with the chamber empty.

On Wide Range Chambers, cooling rate from 23 C (+73 F) to -73 C (-100 F) is approximately 55 minutes, or 1.7 C (3.2 F) / minute. Average heating rate from 23 C (+73 F) to +177 C (350 F) is 3.4 C (6.2 F) / minute, both with the chamber empty.

+ or - 1 C (+ or - 1.8 F) guaranteed control, + or - 0.15 C (+ or - 0.25 F) typical.

Humidity 5% RH to 95% RH, see chart. 95% RH at 85 C (185 F) maximum.

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Optional Equipment

• Window and interior light. Standard sizes are 12 ” x 12 ” and 18" x 18" clear viewing area.
• A window wiper with an external operating handle.
• Access Ports. Sizes are 2”, 3”, 4” and 6.” One 3” access port in the left wall is provided with each chamber.
• A 5-gallon water reservoir with an internal pump, low level sensor, low level alarm, and an isolation valve to allow system operation without a source of pressurized water. The tank requires occasional manual filling.
• A single cartridge, demineralization system that produces up to 4 liters / minute of water. The demineralization system Includes a water purity indicator.
• Casters, two swivel and two fixed.
• Shelf pilasters and wire-type stainless steel shelves.
• LN2 boost cooling with vent for extra or boost cooling (can not be used while humidity is in operation).
• GN2 gas purge with pressure regulator, gauge, flow measuring and regulating valved rotameter, and vent.
• Two refrigeration gauges mounted in the refrigeration compartment with or without isolation valves for the narrow range model or four refrigeration gauges mounted in the refrigeration compartment with or without isolation valves for the wide range model.

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Optional Instruments

Available instrument options include:

• Microprocessor-based, FM Approved, high over-temperature safety control.
• Set of two, one high and one low microprocessor-based, FM Approved temperature safety controls.
• Remote control over an Ethernet Link.
• 12-inch, two pen, chart printing, circular recorder.
• Pre-fixtured relay racks for mounting test items.
• Strip chart recorder.

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Available Literature Includes:

Bemco FW Series, Glass Door Temperature/Humidity Chambers. Document is triple fold front and back, 2 pages, 353 KB download.

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The systems described above are our Standard Models. We make custom equipment to your specifications.  If you have any questions, need assistance in preparing a specification, or have a technical problem you want help with, we are ready.  Our quotations and advice are free.