Attachment_2_-_Government_Revised_Minimum_Requirements.pdf

Environmental Chamber Requirements: 1 meter cube

1.0 General Description

This specification covers the salient design, construction, and performance requirements for a test chamber to be used for subjecting test items to precisely controlled temperature and humidity environments. Capabilities must include automatic control and recording of dry bulb temperature and % relative humidity at any set point within the ranges specified.

2.0 Construction

2.1 Chamber Exterior

The exterior of the chamber shall be sealed to prevent vapor penetration.

2.2 Chamber Interior

2.2.1 The interior liner shall be constructed of Type 300 stainless steel not less than

20 gauge thickness.

2.2.2 The minimum workspace inside dimensions will be 40” wide, 38” high, 39” deep.

2.2.3 All seams of the interior shall be heliarc welded and completely passivated and normalized. All seams shall be penetrant dye tested to insure that they are hermetically sealed. The liner shall be reinforced on the insulation side with ribs and the shelving in the work space shall be capable of supporting a minimum of 150 pounds uniformly distributed and the floor shall be capable of supporting a minimum of 250 pounds uniformly distributed.

2.2.4 Accessories

2.2.4.1 One (1) multipaned viewing window located in the door.

2.2.4.2 Internal low profile light fixture with 2 bulbs with an external switch.

2.2.4.3 Two (2) 4” diameter utility ports equipped with removable stopper located on both sides of the chamber.

2.2.4.4 All interior parts of the chamber that are in contact with conditioned air shall be fabricated of non corrosive material.

2.2.4.5 Chamber shall have a base drain that will connect to the sanitary sewer system for the purpose of capturing the melting ice or other condensation.

2.3 Insulation

2.3.1 The chamber shall be adequately insulated to maintain less than a 2 degree F

(Fahrenheit) temperature variation inside the workspace after stabilization. Stabilization for the purpose of this requirement is defined as the point in which the internal thermal mass (i.e. test item) reaches the program set point of the air temperature; thus, the air temperature and the test item are both equal to the programed set point of the chamber.

2.4 Door and Gaskets

2.4.1 The chamber shall be equipped with a full front opening door of the same construction as the cabinet to provide full access to the workspace. Door shall be hinged on the left side have a replaceable elastomeric gasket to function as the primary door seal.

3.0 Electrical

3.1 Control Circuit

3.1.1 The control circuit shall include the necessary switches, relays and instrumentation for control of the equipment. The control circuit shall integrate a T-

8800 Thermotron controller for local and remote programing. The control circuit shall include a programmable high-low temperature cut-out system that interrupts the profile being run and returns to ambient conditions if the temperature or humidity extremes are exceeded.

3.2 Power Circuit

3.2.1 The electrical equipment shall operate on 208 volt, 3 phase, 60 cycle power.

The power circuit shall be controlled by heavy duty relays which have shunt trip circuit breakers. Motors shall be controlled by full voltage magnetic starters with overload elements, or by contactors with integral overload protection.

3.3 Electrical Wiring

3.3.1 The electrical wiring and components shall conform to the National Electrical

Code. Harness wirings shall be used for all control and power circuits and connections are made at numbered terminal strips.

4.0 Instrumentation

4.1 Operation Location

4.1.1 The instrumentation panel shall be mounted on the door, located on the side of the chamber, that houses the window. All control circuit components requiring operator interface shall be accessible on or from the front of the panel.

4.2 Channels

4.2.1 The chamber shall have a minimum of two 0 to 10 Volt DC output channels mounted on the instrumentation panel using a Bayonet Neill-Concelman (BNC) connector. Channel one shall provide a linear temperature reading of the chamber’s control thermocouple. Channel two shall provide a linear humidity reading of the chamber’s solid state humidity control sensor.

4.2.2 The sensor for the chamber’s control for temperature and humidity shall be fixed in the conditioned space at the location determined by the manufacturer. The high-low temperature cut-out system shall use a fixed mount thermocouple mounted in the conditioned space away from the workspace as determined by the chamber manufacturer.

5.0 Performance

5.1 Temperature Range

From -85 F to 355 F

5.2 Humidity Range

From 20% to 95% throughout the dry bulb temperature range of 45 degrees to 140 degrees F limited by a 45 degree F dew point temperature, also 15% RH to 95% RH at

160 degrees F. The Government will accept up to +/- 5% tolerance.

5.3 Temperature Control Tolerance

To control the dry bulb and wet bulb temperature to within +/-2 degrees F of set point, after stabilization at any selected temperature throughout the entire operating range.

5.4 Temperature Change Rate (Chamber Empty)

5.4.1 Pull Down Rate: From +185 degrees F to -40 degrees F within 15 minutes.

5.4.2 Heat Up Rate: From -40 degrees F to 185 degrees F within 15 minutes.

5.5 Cooling Capacity

The chamber shall have sufficient reserve cooling capacity for absorbing the equivalent of 400 watts at -40 degrees F after temperature stabilization.

6.0 Miscellaneous

6.1 Handbook or Manuals

When the chamber is ready for shipment, the contractor shall furnish two (2) copies of the handbooks or manuals covering the installation, disassembly, operating and maintenance instructions. A complete parts list must also be included in the manuals.

In addition, copies of handbooks and manuals of auxiliary equipment (controls, compressor, etc.) will be furnished CDRL A001.

6.2 Chamber Test

The chamber shall be tested and checked for proper operation and conformance to purchase specifications prior to shipment.

6.3 Installation and Onsite Chamber Test

The supplier shall provide a field engineer to supervise/oversee the installation and startup the equipment, and run all necessary acceptance tests. Final inspection and acceptance shall be at the Naval Undersea Warfare Center Division Newport RI. upon the successful completion of all tests.

6.4 Limit Switches

The chamber shall be equipped with a safety door switch, capable of being operated from outside the workspace, to shut off the condition equipment when the door is opened. It shall be equipped with high-low temperature cutout with manual reset to protect the cabinet against excessive temperatures.