SOW - Sand and Dust Chamber.doc

Statement of Work

Blowing Sand & Dust Environmental Test Chamber

PID 1300186045

The sand and dust chamber will be used in a test laboratory (Electrical and Environmental Evaluation Laboratory, Building 1461, Patuxent River, MD) to provide controlled environments during testing of Naval aircraft/shipboard/ground electrical or mechanical components and systems. The predominant test methods will come from MIL-STD-810 and for sand and dust environments. The results of the testing are used for Naval qualification, safety of flight, flight worthiness, and evaluation programs.

Specifications for the chamber are as followed:

1. Controlled Chamber Parameters. The chamber shall control the temperature, humidity, air velocity and sand/dust concentration levels.

1.1 Temperature. The chamber shall control the temperature between 25°C and 93°C.

1.1.1 Temperature Tolerance. The temperature (return air) shall be controlled within a tolerance of ± 2°C under steady state conditions (after the setpoint temperature is attained with no control changes).

1.1.2 Temperature Rate of Change. The chamber shall be capable of going from room temperature conditions to the maximum operating temperature of 93 °C within 1 hour.

1.2 Humidity. The chamber shall be capable of maintaining humidity levels <30% relative humidity throughout the duration of the temperature profile.

1.2.1 Humidity Measurement. A direct readout sensor (not a dry/wet bulb) shall be used to measure humidity. The sensor shall operate over the required temperature range for humidity control and shall not be degraded or damaged over the operating temperature of the chamber.

1.3 Blowing Dust Testing. Chamber must be capable of fully meeting the requirements of MIL-STD-810G, method 510.5 procedure I.

1.3.1 Dust Media. The chamber must be fully compatible with various dust compositions including silica flour and red China clay with particle sizes up to 150 µm in diameter.

1.3.2 Dust Test Air Velocity. The chamber must have variable control over the air velocity throughout blowing dust testing. The velocity must be variable between zero and a minimum of 1750 ft/min (8.9 m/s).

1.3.2.1 Dust Test Air Velocity Tolerance. The dust test air velocity tolerance must be maintained at ± 10% of the specified value under steady state conditions (after the setpoint air velocity attained with no control changes).

1.3.2.2 Dust Test Air Velocity Rate of Change. The chamber must be able to ramp and hold the air velocity steady between minimum and maximum test air velocities within 2 minutes.

1.3.3 Dust Concentration Level. The chamber must be equipped with controls to adjust the dust concentration from a minimum of 2 g/m³ to a maximum of at least 25 g/m³.

1.3.3.1 Dust Concentration Level Tolerance. The chamber’s controls must maintain the set point concentration level to within ± 7 g/m³ when the typical 10.6 g/m³ of dust is used for the set point.

1.3.3.2 Dust Concentration Level Rate of Change. The chamber shall not take longer than 5 minutes to adjust and hold at any concentration level throughout the operating range.

1.4 Blowing Sand Testing. Chamber must be capable of fully meeting the requirements of MIL-STD-810G, method 510.5 procedure II.

1.4.1 Sand Media. The chamber must be fully compatible with various sand compositions including silica with particle sizes from 150 µm to 850 µm in diameter.

1.4.2 Sand Test Air Velocity. The chamber must have variable control over the air velocity throughout blowing sand testing. The velocity must be variable between zero and a minimum of 5700 ft/min (29 m/s). To ensure the particles impact the test item at the set velocity, the sand injection point must be at least 3m (10 ft) from the test item. A shorter distance can only be used if it can be proven that the particles achieve the necessary velocity at impact.

1.4.2.1 Sand Test Air Velocity Tolerance. The sand test air velocity tolerance must be maintained at ± 10% of the specified value under steady state conditions (after the set point air velocity attained with no control changes).

1.4.2.2 Sand Test Air Velocity Rate of Change. The chamber must be able to ramp and hold the air velocity steady between minimum and maximum test air velocities within 2 minutes.

1.4.3 Sand Concentration Level. The chamber must be equipped with controls to adjust the dust concentration from a minimum of 0.0 g/m³ to a maximum of at least 2.7 g/m³.

1.4.3.1 Sand Concentration Level Tolerance. The chamber’s controls must maintain the set point concentration level to within:

± 0.5 g/m³ at a set point concentration of 2.2 g/m³

± 0.3 g/m³ at a set point concentration of 1.1 g/m³

-0.0/+0.2 g/m³ at a set point concentration of 0.18 g/m³

1.4.3.2 Sand Concentration Level Rate of Change. The chamber shall not take longer than 5 minutes to adjust and hold at any concentration level throughout the operating range.

2. Environmental Chamber. The environmentally conditioned portion (working space) of the sand and dust chamber shall be insulated and accessed by a hinged door. The environmental chamber shall have a stainless steel interior with continuous welded seams so that oil or other fluids cannot seep into the insulation.

2.1 Environmental Chamber Installation. The environmental chamber will be installed on a flat 5 inch reinforced concrete floor.

2.2 Volume. The environmental chamber shall have a minimum usable interior volume of 27 ft³ with minimum interior dimensions for the height, width, and depth of 36.0 inches.

2.3 Circulating Air Blower/Fan. The environmental chamber shall have an internal blower or fan to circulate air within the environmental chamber. The blower/fan shall not protrude into the usable environmental chamber volume. The electric motor for the blower/fan shall be located external to the environmental chamber. The blower/fan shall circulate air to maintain a uniform temperature and humidity within the environmental chamber as defined in section 1. The fan shall have a manual on/off switch and indicator light on the control and display unit.

2.4 Test Section Door. The door shall maximize access to the test section of the chamber. The door shall have an integrated safety switch that disables all chamber systems if opened during operation. The door shall have a manually lockable latching system which will prevent personnel from opening the door while the chamber is operating.

2.4 Windows. The environmental chamber shall have observation windows on two opposite sides to allow maximum visual inspections into the chamber working space. The window area shall be a minimum of 12” x 12” and centrally located on both sides to allow maximum visibility into the test chamber and a straight line of sight through both windows.

2.4.1 Window Wipers. Manually controlled wipers or other provision shall be provided to clear sand/dust build-up from the inside of the observation window’s glass.

2.5 Interior Lights. The environmental chamber shall have interior lighting. The lights shall be positioned to provide uniform light distribution inside the environmental chamber. The lights shall not protrude into the usable interior space of the environmental chamber. The lights shall be controlled by a manual switch located on the control and display unit.

2.6 Access Ports. The environmental chamber shall have four 3.0 inch access ports installed on the sides of the environmental chamber (see figure 1 for locations). The access ports shall be supplied with removable caps or covers (metal) on the outside of the environmental chamber that will seal the environmental chamber when installed. Access ports shall not extend into the usable space on the interior of the environmental chamber.

2.7 Payload.

The environmental chamber test space shall support a minimum test article weight of 200 lbs.

3.0 Control and Display Unit. The chamber shall have a discrete package for controlling chamber operation and displaying setpoint and all environmental parameters. The control and display unit shall control all operations of the chamber as defined in Section 1.0.

3.1 Switches.

The control and display unit shall have manually operated switches to enable/disable the following systems: control power, sand/dust feed, circulator fan, light, heaters, cooling system and dehumidifier. An annunciation light shall be provided for each on/off switch.

3.2 Computer Operation. In addition to local operation, the control and display unit shall accept remote computer entered commands for setpoint and timed automatic operation.

3.3 Data Recording. The chamber shall utilize a system to digitally record and store the following data: temperature, humidity, sand/dust concentration and air velocity to be plotted against time and inserted into reports or other documents as required.

3.4 High/ Low Temperature Limiter. An independent temperature limiter shall be incorporated into the control and display unit.

4. General Requirements.

4.1 Exterior Finish. The exterior finish shall be suitable to withstand an industrial laboratory environment which shall not be adversely effected by fluids such as cleaning solutions or hydraulic and synthetic oils.

4.2 Installation. The sand and dust chamber shall be limited to less than 12 feet in height and shall fit through a 12 foot width door either in a single section or multiple sections. The Manufacturer shall deliver the unit to the government and the government will place the chamber components into the work space identified and then the Manufacturer will assemble the chamber in place. The government will then install all utilities, as per the manufacturer installation instructions/manuals which shall be included.

4.2.1 Start-Up After all utilities are installed on the chamber; the manufacture shall perform an on-site inspection at Patuxent River, MD of the Government’s installation, to ensure correct connection to all utilities. The Manufacturer shall then start-up the chamber and perform on-site performance tests of the chamber systems to ensure all requirements in 1.0 are achieved. Upon satisfactory Manufacturer start-up and performance testing final acceptance of the unit will be by the Government at Destination on-site at Patuxent River, MD.

4.3 Physical Size. The maximum physical size of the environmental chamber and the machinery cabinets will be approximately 25’ long by 15’ wide by 15’ tall. The height, width, and depth of the environmental chamber and machinery cabinet are variable within a maximum limit. The test area has an open high bay with a 17 foot clearance to the overhead lights and utilities.

4.4 Refrigeration. The chamber shall use mechanical refrigeration system(s). All pressure vessels shall be ASME certified. The refrigeration system shall be air cooled or stand alone closed water loop cooled and operate off of the same 480V, 3-phase, 60 Hz power as the rest of the system.

4.4.1 Safeties The refrigeration systems shall have protection for high and low pressure, low oil pressure, and high discharge temperature. A pressure relief valve shall be provided for the refrigeration system(s). An enunciation light shall indicate refrigeration trips with a reset button for setting the tripped safety.

4.4.2 Refrigerants. The refrigerants used shall be hydrogenated chlorofluorocarbons (HCFC's) or equivalent. Chlorofluorocarbons (CFC's) shall not be used. Refrigerant types shall be marked on the nameplate of the compressors and refrigeration charge information shall be marked on the machinery cabinet.

4.4.3 Gauges and Sight Glasses. Clearly visible gauges and sight glasses shall be provided for maintenance of the refrigeration system.

4.4.4 Piping Insulation shall be used on cold piping to reduce condensation and guard(s) shall be used to prevent hot piping from unintentional touches from personnel.

4.5 Electric Power. The chamber shall operate from 480 volt, three-phase, 60 Hz power. A main power disconnect with an externally accessible switch shall be provided on the machinery cabinet. A terminal block shall be provided to connect a government supplied electric power cable. The electric power terminals shall be clearly marked. The electrical power cabinet shall be accessible from above for main power connections conduit.

4.5.1 Wiring. All wiring used in the chamber shall meet NEC standards.

4.6 AC Power. The chamber shall not be damaged by application of electric power with reverse phase rotation. The chamber shall not be damaged with one or two phases of the three-phase AC power missing (blown fuses). All chamber systems shall shutdown and not attempt to restart in the event of an AC power interruption or abnormal AC power (blown fuse on one or more phases). A manual reset shall be required to restart the system.

4.7 Heater Interlock(s). An independent controlled high heat limit interlock shall be provided to prevent over temperature of the chamber or damage to heating elements.

4.8 Fan Interlock. An interlock shall be provided to prevent operation of the chamber with the fan not operating.

4.9 Circuit Protection. All circuits in the chamber including the control and display unit shall be protected with circuit breakers or fuses.

4.10 Operating Environment. The chamber shall operate in unconditioned spaces (limited heat and no air-conditioning) with ambient temperatures above freezing to 46.1°C.

4.11 Fluid Compatibility. The interior of the environmental chamber, including seals/gaskets, shall be compatible with synthetic engine oils (including MIL-L-23699), oil vapor, lubricating greases, water and water vapor, and industrial cleaning compounds. All components in the chamber shall be compatible with an industrial test laboratory environment.

4.12 Maintenance. All chamber systems shall be maintainable by the government. All subsystems shall be accessible for maintenance without removal of major components. All interior and exterior electrical and mechanical interconnections shall be clearly and permanently labeled.

5.0 Operation and Maintenance Manuals. Two bound manuals, as well as an electronic copy, shall be provided that contain a detailed description of the operation and maintenance requirements for the chamber. The manual shall include operating instructions, routine and overhaul maintenance requirements, troubleshooting procedures, electrical wiring and mechanical schematics, dimensioned drawings, parts lists, chamber specifications including subsystems, subsystem data sheets, interface requirements, calibration requirements and procedures, and complete instructions for programming the chamber either locally or via personal computer. The manual shall also contain a list of recommended spare parts and materials that would be required for routine maintenance.