Conditioning
Chamber air is recirculated by a high volume, stainless steel axial fan discharging through a hinged rear mounted guard and 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. Fast-response open type heaters, located behind a radiation baffle, raise chamber temperature as required.
Cooling
Chamber temperature is reduced by a proportionally controlled liquid nitrogen injection system utilizing both a control solenoid and a series mounted safety solenoid to positively interrupt nitrogen flow in the event of a malfunction. A relief valve and a line strainer are provided for dependable operation. A self sealing vent system with an attachment coupling for remote piping by others removes expanded nitrogen from the workspace.
Construction
LDF Series chambers include a 304 Series stainless steel welded liner with high temperature fiberglass insulation. No asbestos is used in chamber construction. Outer cases are fabricated from cold rolled steel finished in Bemco Blue. Chamber doors feature Bemco’s plug door to minimize problems with expansion and contraction on the door face and dual gaskets to greatly reduce thermal losses near the door face. An over-center Bemco cam-type latch seals the door.
Safety Systems
All electrical wiring meets the United States National Electric Code. UL and CSA approved components are used where possible.
Controls
Each Bemco LDF chamber is furnished with a 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 LDF chamber is sensed by a precision thermocouple. An RS232 and RS485 interface is standard. Heaters are interlocked with a separate heavy duty power contactor and a factory preset high temperature safety control.
Thermal Performance
Cooling rate from 23 C (+73 F) to -73 C (-100 F) chambers is approximately 15 minutes, 6.4 C / minute (11.5 F / minute) average. 23 C (+73 F) to 177 C (350 F) in approximately 30 minutes, 5.1 C / minute (9.2 F / minute), both with the chamber empty.
+ or - 1 C (+ or - 1.8 F) guaranteed control, + or - 0.3 C (+ or - 0.5 F) typical.
Optional Equipment
- Window and interior light. Window sizes are 12" x 12" and 18" x 18" Clear viewing area.
- Access Ports. Sizes are 2", 3", 4" and 6." One 3" access port in the left wall is provided with each chamber.
- A caster base to allow convenient chamber movement. The caster base includes four swivel casters. Caster bases are available on LDF8’s to LDF64’s.
- A fixed base to support the chamber at a convenient work height.
- Shelf pilasters and wire-type stainless steel shelves.
- GN2 gas purge with pressure regulator, gauge, flow measuring and regulating valved rotameter, and vent.
- Desiccant drier purge with dual tower 10 cfm desiccant drier, pressure regulator, gauge, flow measuring and regulating valved rotameter and vent.
Optional Instruments
Controls are mounted on the side to prevent dripping from damaging the instruments. Available instruments 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.
- Custom fixturing, load boards, and card cages to match your load.
- 12 inch, chart printing, circular recorder.
- Strip chart recorder.
Available Literature Includes:
Bemco LDF Series, Expendable Refrigerant Temperature Chambers. Document
is triple fold front and back, 2 pages, 319 KB download.
Bemco Temperature Conversion Table. Temperature conversion chart
for -273.15 C (absolute 0) to +548.89 C (1020 F) in 10 degree increments.
Document is 1 page, 336 KB download.
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.
