Portable Temperature Conditioners

Bemco PTS-V Portable Servo Conditioners provide a closed loop flow of controlled temperature air or gas to an insulated enclosure or structure. Bemco high pressure gas servo conditioners provide air or gas at up to two atmospheres of pressure to heat exchangers and thermal shrouds. Bemco HPG High Pressure Gas Conditioners are described on a separate page.

The standard line of PTS-V Portable Temperature Servo Conditioners feature a number of outstanding, sometimes Bemco exclusive, features that make them easier to use, more reliable, and more precise than ever before.

Every PTS-V includes an adjustable variable speed drive motor on the blower to allow precise flow balancing. The interior conditioning structure is easily accessible through a large insulated hinged door and on heat exchanger models, liquid nitrogen use is conserved by a separate liquid nitrogen level control system.

PTS-V’s are furnished as free standing caster mounted systems. They feature a 304 Series stainless steel welded liner with high temperature fiberglass insulation. No asbestos is used in construction. Outer cases and machinery enclosures are fabricated from cold rolled steel finished in Bemco Blue. Conditioning compartment doors include dual gaskets to greatly reduce thermal losses near the door face. Four swivel casters with wheel locks are standard on all models.

All electrical wiring meets the United States National Electric Code. UL and CSA approved components are used where possible.

The table above shows the standard "expendable refrigerant" systems that use liquid nitrogen (LN2) for cooling and the table below shows the "mechanically cooled" systems. The last column in the above table for "expendable refrigerant" systems titled "Circulating Gas" refers to the combination of the type of gas circulating in the system (Gaseous Nitrogen - GN2 or Air) and the cooling technique (direct injection of liquid nitrogen into the circulating gas - Direct; or the use of a liquid nitrogen heat exchanger to allow the primary loop to circulate air - LN2 Hx.

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Air Circulation

Air is recirculated by a high pressure, non-sparking aluminum blower mounted in a scroll discharging through an appropriately sized duct cuff. Air is returned to the conditioner through a second, matched duct cuff. Insulated duct pairs and duct clamps for attachment to your test load are available as an option.

The blower is driven by a vertically mounted motor with dual ball bearing races, connected by a large diameter extended stainless steel shaft. Motor speed and total system air flow can be adjusted to match load conditions. A minimum flow is required to prevent heater burnout.

Fast-response, open type heaters, raise temperature as required.

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Instrumentation

Each PTS-V includes a microprocessor based, programmable 1/4-DIN, solid state 256-step ramping controller with a 4-line LCD interface display and a large red LED display. An RS232 and RS485 interface is standard. The protocol is Modbus™. LabVIEW™ drivers are available.

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

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LN2 Cooling

For those systems that have liquid nitrogen cooling, either a direct nitrogen injection system or a liquid nitrogen heat exchanger is supplied.

Liquid nitrogen systems include dual liquid solenoids, one for proportional control and one to act as an interlock to prevent run away in the event of a solenoid failure. A liquid line strainer and a relief valve are also included.

When an air to LN2 heat exchanger system is selected, a liquid nitrogen level control system is provided. The level control system prevents fluid blow-through in the event that the heat exchanger system is calling for more cooling but is already full of liquid nitrogen due to previous demand. Air to LN2 heat exchanger systems are specified when you prefer air as the circulating medium.

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Mechanical Cooling

Mechanically refrigerated systems are selected when operating cost versus first cost is a primary consideration. Mechanically refrigerated systems can be optionally furnished with liquid nitrogen boost cooling to allow operation down to -180 C. In some cases, special provisions must be made to isolate the refrigeration system from this cold temperature.

When a mechanically refrigerated system is specified, a proportionally controlled cascade, two compressor, refrigeration system for -70 C ultimate temperature systems, or a single stage, one compressor refrigeration system for -35 C ultimate temperature systems is provided. These systems utilize modern environmentally friendly refrigerants to cool the circulating air or gas. The refrigeration system includes automatic hot gas bypass and suction cooling unloading. Cascade systems also feature Bemco’s exclusive, high performance coaxial cascade heat exchanger.

All systems have thermal and current sensors on each compressor as well as numerous safety and reliability protection systems for dependable operation. Standard systems all have water cooled condensing. Air cooled condensing is optionally available.

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Humidity Option

Mechanically cooled PTS systems can be specified with humidity control. If this option is selected, humidity is increased by a Bemco mass transfer vapor generator and decreased by the direct injection of -73 C (-100 F) dew point dry air using a heatless, dual tower, desiccant drier.

The vapor generator includes a stainless steel insulated tank connected to the PTS conditioning system by an insulated tube that allows water vapor to migrate into the conditioned process air. The system has a sight glass, a low water cutoff, and automatic drain freeze protection. It can also be shutoff and drained when very low humidity control is desired. Humidity is increased by the proportional cycling of the vapor generator heater.

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). The maximum humidity range offered over the temperature range of 5 C to 85 C is 5% RH to 95% RH with the ability to reach 5% RH at 5 C. To achieve these conditions, the attached enclosure, ducts and the servo conditioner must be very tightly sealed.

The standard humidity range is 20% RH to 95% RH limited by a 5 C dew point and an 85 C maximum dry bulb temperature.

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Matching Enclosures

Thermally insulated enclosures matched to selected PTS Portable Thermal Conditioners manufactured from temporary materials or fabricated using the same high quality techniques employed on Bemco’s LDF Series of Temperature Chambers, as well as the construction methods used on the FL Series of Integral and Modular Walkin Chambers are available. Additional information on these enclosures can be viewed on the LDP Insulated Enclosure page on this Web Site.

Thermal Base Plates and Thermal Shrouds for use with an HPG Conditioner are also offered. Additional information on Shrouds and Thermal Base Plates is given on the AH page of this Web Site.

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Mechanical Options

• A set of two appropriately sized insulated ducts with duct cuffs and clamps for both ends. Standard duct length is 8 feet each.
• Desiccant drier purge with dual tower 10 cfm desiccant drier, pressure regulator, gauge, flow measuring and regulating valved rotameter and vent.
• Refrigeration gauges (two per compressor) mounted in the refrigeration package.
• GN2 gas purge with pressure regulator, gauge, flow measuring and regulating valved rotameter, and vent.

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Optional Instruments

• 24 hour or 7 day, digital indicating, self chart printing, circular recorders for temperature.
• Single-pen or multi-pen strip chart recorders.
• Programmable logic control sequencing of test processes. Bemco recommends Allen Bradley (ABB) PLC’s and software.
• Gas flow volume, or mass flow, display or control instruments.
• Set of two, one high and one low, microprocessor-based, FM Approved temperature safety controls.
• A low flow safety control with an audible and visual alarm system.
• Touch screen HMI’s (human machine interfaces).
• RS232, RS485, and Ethernet communication interfaces.
• Engraved or silk screened graphic control panels.

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Gas Distribution Panels

Optional gas distribution panels and gas control panels are offered to individually distribute, monitor, and protect one or more of your valuable products from higher than required gas flow or process conditions.

You can also use these units with any other source of temperature controlled gas including other manufacturer's products. These systems are individually assembled to match the equipment being tested. They can be designed for mounting in standard Electronic Industries Association (EIA) 19” or 24” relay rack consoles or as free standing, wall, table, or floor mounted systems. A separate Web page describes these units. Please click here.

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Available Literature Includes:

Bemco PTS and HPG Series, Portable Temperature Servo Conditioners and High Pressure Gas Servo Conditioners. PTS Servos provide a closed loop flow of controlled temperature air or gas and HPG High Pressure Gas Servos provide a flow of temperature controlled high pressure gas. HPG gas conditioners are commonly used with Space Simulator thermal shrouds. Maximum standard temperature range is -185 C to +150 C. Higher temperatures are available on request. Sixteen standard PTS and twelve standard HPG models are available. Gas distribution panels are also discussed. Document is 8 pages, 676 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.