SF6_Gas_Recovery_Trailer.pdf

SF6 Gas Recovery Trailer Specs

MECHANICAL SYSTEMS

The unit shall be capable of recovering 99.99+% of SF6 gas from circuit breakers, without any oil lubricated or refrigerated device. The unit shall be designed to perform its intended functions while operating over the environmental range of - 20°F to 120°F, in humidity as high as 100%. The cart shall be designed in such a way that no operator error can result in damage to the cart.

Self-Evacuation

Prior to removing the SF6 from the electrical equipment, the unit shall evacuate air and moisture from its own storage vessel, associated piping, and fixtures, in accordance with the attached schematic diagrams. The final pressure in the unit shall be no greater than 0.1 Torr.

The unit shall be capable of removing an indefinite amount of SF6 from electrical equipment. This process shall remove 99.99+% of the SF6 without any oil contamination by utilizing a compression system with a compression ratio of 10,000:1 or greater. The final pressure within the electrical equipment after removing the SF6 shall be no greater than 0.1 Torr. This final pressure must be achieved while simultaneously reaching discharge/storage pressure of 725 PSIG.

Evacuation of Air from Electrical Equipment

The unit shall be capable of evacuating air and moisture from electrical equipment. The final pressure within the electrical equipment, after removing air, shall be no greater than 0.1 Torr.

Charging the Electrical Equipment

The unit shall be capable of returning the SF6 originally removed from the electrical equipment back into the breaker without ANY oil and/or air contamination.

Transfer SF6 from Cylinders

The unit shall be capable of transferring SF6 from cylinders to internal or external storage.

Shall be capable of directly liquefying SF6 into the container, without the assistance of cooling devices (i.e. refrigeration or heat exchangers).

COMPONENTS

Storage Tank

The storage vessel shall consist of multiple DOT approved SF6 cylinders, manifold together, certified to withstand at least 1,000 psi*. All storage vessels must contain the following:

a. Isolation valves

b. Weighing scale

c. Pressure gauge

d. Safety valve

Liquefaction shall occur by pressure only, therefore there shall be no need for refrigeration systems or heat exchangers of any type. The storage tank will not include such things as:

a. Temperature gauge(s)

b. Tank heater(s)

c. Refrigeration coil(s)

To allow extraction of liquid SF6 from cylinders, each cylinder shall be equipped with a dip tube.

To remain legal, it is preferred that the storage system consist of a series of manifold DOT approved cylinders in lieu of one large tank. The cart shall be provided with a weighing tray which stores bottles in a horizontal position.

Vacuum Pump

The vacuum pump shall have a minimum performance rating of 117 CFM. The vacuum pump shall have a final vacuum pressure no greater than 0.1 Torr. The output of the vacuum pump and its associated plumbing shall vent to atmosphere. The vacuum pump shall be designed to extract only air and mois-ture. Under no circumstances shall the vacuum pump be used to evacuate or remove SF6. The cart must be designed to prevent this from occurring. This further prevents any possibility of oil contamination of the SF6. The unit shall come with over-pressure protection sensors at the input of the vacuum pump.

Safety relief valves shall not be permitted as protection for over-pressure. A normally closed, statically sealed solenoid valve shall be placed at the input of the vacuum pump.

In the event that a positive pressure exists, the cart shall detect the positive pressure and prevent the solenoid from opening, thus protecting the pump. This solenoid valve shall be vacuum tight, and serve as an anti-suck back valve in the event of power failure. This shall be in addition to any anti-suck back mechanism available in the pump itself.

Suction Pump

To guarantee a 10,000:1 compression ratio, an oil-less, hermetically sealed dry running suction pump shall be mandatory. Because vacuum pumps are oil-diffusion type pumps, which add oil to the gas stream, only a 100% oil-less device shall be used. The suction pump shall be placed in-line with the main compressor, to aid in the vacuum stage of gas recovery-based functions. It shall include automatic by-pass valving and automatic on/off throttle valve operation using pressure-controlled sensors. This allows for the remaining SF6 within the breaker to be removed without oil contamination and without further input by the operator. The final vacuum shall be no higher than 0.1 Torr. This component shall not be used to remove air after breaker maintenance.

SF6 Compressor

The main gas compressor must be hermetically sealed and 100% oil-less. It should be capable of generating an unassisted 50:1 compression ratio. Together with the vacuum compressor, it shall be capable of generating a compression ratio of 10,000:1. There shall be absolutely no oil in the compressor, crankcase, compression chambers, motor, gears, or any other part of the compression system. Crankcase heaters shall not be permitted. The compressor shall have a maximum discharge pressure of at least 725 psi, while simultaneously pulling down to atmosphere (0 PSIG) at the input. The liquefying compressor shall be self-sufficient in liquefying the SF6 without the assistance of any thermodynamic system (i.e. refrigeration and heat exchangers). Therefore, any refrigeration, heat exchanger, or other device designed for cooling the SF6 shall not be permitted.

The compressor shall be equipped with a switched discharge pressure gauge (max. pressure 800 psi), which shall turn the unit off if its maximum preset pressure is exceeded. The compressor shall have no oil seals, and shall be gas tight under positive or negative pressure, when power is turned off.

The entire compressor unit (motor, pistons, and all moving parts) shall be enclosed in one, pressure sealed housing. Because crankshaft seals of belt-driven compressors develop leaks (air/moisture intrusion, and/or SF6 leakage), under no circumstances shall belt-driven compressors be permitted. The compressor shall not be driven by compressed air/nitrogen. The SF6 compressor(s) must have a throughput rating of 35 CFM or more.

Evaporator

A thermostatically controlled evaporator shall be placed between the storage vessel and the compressor section for refilling SF6 from the gas cart back into the equipment. The evaporator must be designed to allow entry of liquid SF6 and release of gaseous SF6 at a temperature range between 65°F and 75°F. The minimum gas flow rate must be 400 lb. SF6 per hour. A thermostat must maintain the outlet temperature of the SF6 within 65°F and 75°F. Should the gas temperature drop below the range, a solenoid valve in front of the evaporator must automatically close to prevent liquid SF6 from being further transferred. The solenoid valve must be reopened automatically if the gas temperature is within the range again. The entire evaporation system must function automatically. No operator intervention shall be required. No special precautions shall be taken to safely shut down, start up, or operate the cart.

Filtration System

The cart shall come equipped with three (3) field replaceable filter cartridges. The main filter (known as “drying filter”) must be capable of processing decomposition and moisture contamination and be located between the compressor and storage section of the gas service cart. Under no circumstance will the filter be positioned after the storage section. The drying filter medium will consist of two parts: 1.7 kg aluminum oxide (Al2O3) at a 20-50 Angstrom granular size (2-5 mm) to remove moisture, as well as 0.6 kg molecular sieve with a pore size of 4 Angstrom to remove decomposition products. One inlet particle filter (filtering particulate solids down to 1 micron) must be located at the input section of the service cart, and another one (1) micron particle filter shall be placed at the output of the SF6 drying filter. Because of the serious and potentially destructive effects of heating any filter materials, filters shall NOT be designed for regeneration. Switching of filter cartridges should be possible without opening and re- tightening tube unions. Because all filters are, by nature, more efficient at higher pressures, they shall be pressure rated and operated up to 800 psi. The filters shall be capable of drying SF6 to -50° C dew-point with one pass. Therefore, it shall not be necessary to circulate the gas to purify it.

The cart shall be equipped with an automatic feature to depressurize the filter housing prior to service and evacuate the filter housing after service.

For safety reasons, both filter locations shall be equipped with their own analog pressure gauge.

PIPING

Pressure Regulator

A pressure regulator, adjustable between 0 and 145 PSIG, shall be provided at the discharge port to allow full control of the output pressure of the cart. This prevents over-pressurizing the electrical equipment during the refilling process.

The pressure regulator must be located on the control panel, and should allow for quick, easy, and accurate adjustment. The set pressure shall be indicated digitally on the main touch panel interface.

Relief Valves

The cart shall be equipped with TÜV CE approved safety valves at all critical locations. Except for the tank/cylinder safety valve, all relief valves shall return over pressure back to a lower pressure point in the unit to avoid gas loss. All relief valves shall be self-resetting.

Shut-Off and Control Valves

Any shut-off and manual control valves shall be one-quarter turn world renowned gas-tight DILO valves, pressure rated at 725 psi. There shall be no more than one

(1) manual valve per gas processing unit.

Sealing System

To eliminate leakage caused by vibration, metal valves requiring additional sealants (National Pipe Thread [NPT], 37° flare [JIC], etc.) shall not be permitted anywhere on the processing system. All couplings, unions, and fittings shall incorporate DILO’s exclusive metal to metal sealing system.

This will ensure compound free, vibration-resistant, gas-tight seals. All terminating fittings shall end in, greater than or equal to, DILO’s self-sealing couplings, allowing for the removal of hoses from the cart without the loss of positive or negative pressure (full range of 1500 psig to 0.1 Torr).

Manufacturer shall guarantee, for the life of the cart, that fittings will not develop leaks.

Fittings MUST NOT require periodic re-tightening.

Plumbing

Since decomposed SF6 is highly corrosive, only silver solder shall be used in soldering piping together. No internal component shall be supported by its associated plumbing. Any runs of plumbing greater than one foot must be securely mounted to the frame of the cart. To eliminate the potential of operator error, there shall be only one port from which recovery of SF6, evacuation of air, and recharging with SF6 shall be conducted.

Solenoids which are used to replace manually operated valves shall be normally closed, and statically/hermetically sealed, to prevent moisture and/or air intrusion, and/or SF6 leakage. They shall be designed to close (at pressures up to 1500 psig) when a loss of power occurs. No rubber hoses shall be used downstream of the output side of the drying filter housing.

Service Hose

Unless specified otherwise, two (2) 16-foot hoses shall be supplied with each gas cart. Each hose must have the, greater than or equal to, DILO self-sealing, metal to metal connector, one on each end. The hose shall be no smaller than 0.8-inch I.D. Hoses shall not require a positive pressure to prevent air intrusion.

INSTRUMENTATION AND CONTROLS

Touch-screen Operation

The touch-screen shall be accessible via a 10” color touch-screen interface and must include the following four (4) operating modes:

• Manual

• Gas recovery

• Evacuation of air

• Filling of gas

• Reduce gas

The control system must also have the following “special” functions available for automatic

Operation:

• Recovery to transport pressure

• Recovery of filters

• Evacuation of filters

• Evacuation of device

• Rinsing of compressor

• Pressure test of compressor

• Pressure compensation of device

No operation shall require more than two (2) working steps. No special precautions shall be necessary to operate the cart. It shall be possible to connect to a fully charged breaker without the need to check valve positions, or to follow a check-list.

All functions shall be selected, initiated, and terminated via the touch-screen interface. The touch screen interface shall contain icons used to select/deselect each function and change color to indicate on/off position. In manual mode, the operator shall be able to manually control individual solenoid valves and components, by pressing the corresponding icon.

The cart shall be designed so that once an operation has been selected and started, there shall be no need for operator interaction. The cart shall be capable to run without operator supervision.

Therefore, there shall be no steps in the operation of the cart which require the presence of an operator (i.e. throttling of valves). To prevent damage to any component during unattended operation, the following automatic protection features shall be included:

• Pressure and temperature protection of compressors

• Oil back-flow prevention for vacuum pump

• Pressure cut off to protect vacuum operation under pressure

• Solenoid valves which automatically close with loss of power

• Phase rotation relays for directional motors

• Resetting safety-valves which vent to low pressure side of cart

ELECTRICAL CONTROL PANEL

All electrical controls (PLC, Circuit Breakers, Relays, and Contactors) and touch-screen interface for the touch-screen control shall be located on or behind the door of the electrical control cabinet.

INSTRUMENT PANEL

The instrument panel shall be located at the front of the unit right next to the electrical control panel. Colored icons shall be placed strategically on the display.

These icons shall serve two functions: (1) to clearly indicate gas path, and (2) to let the operator choose the gas path if manual override is desired. All operations shall be controlled and monitored by the cart. The design of the cart shall prevent any damage from incorrect operator selections.

Optional Equipment:

The control system shall be capable of incorporating automated controls including: automatically stop the recovery system at user adjustable blank off pressure, evacuate breaker to user adjustable level, perform vacuum rise test and automatically fill to user specified level.

The control system shall be capable of displaying dew point of SF6 exiting onboard dryer filter and alert the user that the filter requires replacement.

TRAILER BRAKES

The trailer shall be equipped with electric brakes. The system shall include a breakaway circuit with a rechargeable battery.

TONGUE ASSEMBLY

The tongue shall be equipped with a 3 inch Pintle Hitch. The eye shall be rated for 10,000 pounds GVWR. An adjustable tongue jack shall be provided. The jack shall be rated for no less than 2,000 pounds.

STABILIZING JACKS

The trailer assembly shall be equipped with two (2) stabilizing jacks mounted on the rear bumper.

Both jacks shall have a rating of no less than 2,000 pounds each.

TRAILER WIRING

All lights and reflectors required by U.S. DOT, 49 CFR, shall be furnished. The electrical connector shall be the 7-conductor type wired in accordance with SAE J560. The trailer electrical system shall be 12 volts nominal. Wire size shall be No.

12 AWG. Joints shall be soldered and covered with heat shrink tubing, and grommets shall be unitized at penetrations through steel frame and body members.

ENCLOSURE

A weatherproof aluminum enclosure, with split rear door and side access door. All doors shall be lockable and designed to make the enclosed area of the trailer weatherproof from inclement weather and road spray at 55 miles per hour.

Outer aluminum walls shall be supported by an internal channel steel frame with interior surfaces covered by ¾” plywood. Floor shall be 3/16” steel diamond plate.

Gas processing unit shall be able to be removed with a forklift without removal of the enclosure.

QUALITY CONTROL, WARRANTY, & MONEY-BACK-GUARANTEE

All exterior metal surfaces shall be thoroughly cleaned of rust, scale, weld splatter, and all oil and grease prior to applying the paint priming coat. The exterior shall be spray painted with highly visible orange paint, unless specified otherwise.

The cart shall be provided with a one year full warranty on all parts and labor. In addition, the cart must be provided with a life-time warranty against any leakage.

In addition to all warranties, standard recovery units shall also be furnished with a 30-day money-back- guarantee. If during the first 30 days it is determined that the supplied cart does not meet this specification, or the buyer is not satisfied with the performance of equipment, the vendor shall take back the unit at no cost to the buyer.

OPERATION

The unit shall be functionally tested prior to shipment. All test certificates and papers shall be sent to end-user.

LEAK TEST

In addition vacuum testing, the unit shall be leak tested under positive pressure.

To pass final testing, the leakage rate of the complete system cannot exceed 1 x 10-5 mbar*l/s. After which, the cart shall be charged with dry SF6, and sealed.

INSTRUCTION BOOKS

Two instruction books shall be provided with each cart purchased. The books shall provide instructions for maintaining and servicing the unit, and to provide information and recommendations for use by the end-user.

TRAINING

SF6 safety class and hands-on training shall be provided at the customer’s location once the cart has been delivered, at no additional charge.

DRAWINGS

Complete assembly drawings and full electrical schematics shall be provided with the unit.

ELECTRICAL SYSTEM

The operating voltage shall be 240 VAC @ 60Hz 3 phase. The electrical system shall be protected by independent component breakers, as well as a main circuit breaker. All motor circuits shall be protected by thermal overload devices.

TRAILER ASSEMBLY

The trailer shall be capable of highway travel at speeds up to 55 miles per hour, with the storage tanks full of SF6.

TIRES AND WHEELS

Tires shall be rated for the trailer weight and be of radial type, including the spare tire. Wheels shall be disc type. The tires shall be mounted to provide a minimum of 3 inch clearance.

Spare Parts

Manufacturer shall provide a spare parts list.

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