“DEcon systems available with 8, 50, 200, 350, 500 gallons per hour and higher.” NEW,, an 8 gph EDS that can fit under a counter for upgrading existing lab Or for small new lab”
1.1 Operating Sequence
A. General:
- The collector tank is constantly receiving liquid from the bio-containment facility. The tank is continuously pre-heating the liquid to 200 degrees F until the 225 gallons capacity is reached, it is then drained to the cooker. At all times the collection tank is vented to atmosphere through a Pall or equivalent membrane filter. When the tank fills, it breathes out through the filter. When the collection tank drains, it breathes in from the Cooker tank.
- Once the cooker has been filled, a cook cycle commences. The Treatment Cycle includes raising the temperature to set point and holding for the timed duration.
Once the time and temperature parameters are met, the liquid is ready to transfer to the cooling tank. Because the cooling tank is of the same pressure rating, we can make the exchange without a delay. The cooling tank vents to the Cooker tank as the drain is opened and allows the transfer. The Cooling tank will cool the liquid to a discharge temperature of 145 degrees F. Co-flush can be added to accommodate draining at an elevated temperature if desired.
- If either the high temperature or high pressure sensors are activated, the process high limit indicator shall be illuminated on the display screen and the PLC shall notify the Building Automation System (BAS) of the condition. This shall be a latching alarm condition and require manual reset.
B. Fill Mode:
- When the Cooker tank is able to receive effluent from the gravity drain, the appropriate valves divert the effluent to the Cooker tank.
- The liquid passes through a trash valve (full flow ball valve) then through a second isolation valve prior to entering the tank.
- The batch fill volume of the Cooker Tank is sensed by the piezoelectric liquid level detection system. Once full, the trash valve closes, and a power-flush of the isolation valve flushes any impurities from the fill line and valve into the tank, assuring that the valve seals are clean, and then the isolation valve closes.
- Any additional effluent will be held in the collection tank until the cooker is again available to receive the next volume of material to be cooked.
- During the fill mode, air trapped inside the Cooker tank is rerouted to the Collection tank via a loop just under the combined Vent filter.
C. Heat Mode:
- Once the cooker is filled and the isolation valve is closed, the circulating hot oil will elevate the temperature to set point. Since the liquid temperature is already near pressure temperature the Cooker is instantly closed off.
- The cooker will continue to heat until the prescribed process temperature and pressure are achieved (normally 255 degrees F or higher; user set) and the process time is satisfied (normally 30 minutes or longer; user set). A minimum cycle parameter available to the user is 255 degrees F for 30 minutes cook time.
- Because the Cooker tank is never cooled, cycle times and energy consumption are held at the highest efficiency. Sterilization of all connecting pipes and valves is achieved by maintaining this high temperature.
- The system shall constantly compare the temperature and pressure within the Liquid Decontamination Tank to insure saturation conditions are constant and normal. During the cook cycle the minimum cycle temperature will be maintained or exceeded for the set period of time. If at any time the temperature dips below the set temperature, the timing of the cycle will cease until the temperature again reaches the set temperature level. This condition will generate an alarm that there is a problem. Whichever thermocouple is at the lowest temperature is the control thermocouple for the cycle
D. Cooling Mode:
- The Cooling tank is constantly cooled by circulating chilled or cold water. Cooling is easily achieved with chilled water, however, if desired the water could be elevated to drain utilizing the pressure of the liquid through a Sparger and cooled via a co-flush instead of a lift pump.
E. Discharge Mode:
- The discharge mode will open the drain valve on the Cooling tank.
- The tank is discharged by gravity or vessel pressure. Temperature is monitored during discharge and a co-flush valve adds cold water so that the discharge temperature meets local sewer codes (i.e., 140 degrees F, user settable).
- Once discharged, a cold water rinse flush flows across the bottom of the tank to flush and remove any settled solids from the cooker tank. Once the tank level indicates empty and a cycled time flush is complete, this process terminates and the tank valves are closed.
- The piezoelectric level sensors on each tank allow for independent filling and draining to speed the system along.
1.2 High Pressure Relief (Pop-off) Sequence
A. If the pressure in the tank should exceed the set-point of the rupture disc (75 psig), the relief will be extremely hot but sterile. The relief vent may be run to the floor underneath a unit, and the room will fill with steam in the event of a pop-off. Because the system is rated at 75 psi, and the safeties are at 50 psi, well below that, a pop-off is very unlikely to ever happen. The pop-off may be vented to the roof and directed to the sky, but a flap on the end of the pipe is necessary to prevent water from filling the pipe. Such a pop-off would allow the liquid to cool as it blows out; a safe way to vent. The vent can be run into a tank but is not really necessary. If it runs to a tank the tank should have a large vent opening in the top to allow the steam to escape and capture the liquid. This tank should not be restricted or filtered. Filtering is unnecessary, and could be dangerous. Some local regulations may require the tank to be a pressure rated blow-down tank which can be provided. If a filter is required, it should be an HVAC filter rated for high moisture service, but with a failure pressure of 15 inches of water column, to prevent back-pressuring the system. A burst indicator mounted in the line shall indicate that a pressure relief has occurred. When a pressure relief occurs, the pop-off alarm indicator on the touch screen will be illuminated and the information will be sent to the building data system. This shall be a latching alarm and require manual reset. Once the tank pressure falls below 75 psig, the ASME rated relief valve will close to contain the remaining pressure. Should pop-off occur, a new rupture disc would be installed and the cause of the high pressure relief shall be determined and corrected before manual resetting.
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