MK Plastics Venturi IO&M - Manual (Page 4)

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Venturi Wash Controller (if supplied)
Perchloric acid is extremely dangerous because it is a very strong oxidizer. Dry perchloric acid crystals are unstable,
and when subject to shock or vibration, can explode. For this reason the Venturi stack is supplied with a washing ring
and spray nozzle for periodic washing (flushing) of the duct work to remove accumulated wall deposits, which are
soluble in water. The ‘MVT Plastifer Perchloric Acid Wash Controller’ used in conjunction with the Perchloric Acid
Exhaust Venturi system, safely and automatically washes perchlorates from the system. This control package can be
supplied by MK Plastics. See Fig. 4 to Fig. 5 for details.
Through the use of a field programmable microprocessor, wash water is directed via solenoid valves to each wash
point in the venturi system. When the researcher shuts off the MVT Venturi exhaust fan, the wash system is
energized, sequencing wash water to be directed to the venturi wash ring first, the inlet venturi wash nozzle, second,
and then the auxiliary duct mounted wash rings. This wash cycle continues in descending order (from the top of the
system to the bottom) toward the perchloric fume hood. Wash duration per wash nozzle is fully programmable.
Wash Controller Specification
1. Control unit shall be enclosed in a NEMA 1 enclosure that shall be remotely mounted and located in the
laboratory. The control panel shall house the microprocessor, electronic switches and wiring terminals. The
panel shall have controls consisting of MVT blower Manual/On-Off switch, indicator lights, and
microprocessor display per fan, all mounted on enclosure door. Power input shall be 120 VAC.
2. Interconnecting wiring between the controller and wash solenoid panel, and the water piping between the
wash solenoid panel and the wash rings shall be the responsibility of the installing contractor.
3. A facility safety engineer shall determine the wash cycle duration and the wash duration of each nozzle.
The safety engineer shall then insure the correct programming of the wash cycle.
4. The wash cycle can be fully programmable, or have manual override by pressing the stop button.
5. Upon blower shut down, the wash system sequence shall be initiated, energizing the respective solenoid
valve, starting the wash cycle at the highest wash nozzle, and continuing down through all the wash nozzles
and rings in the perchloric exhaust system. The user has the option to have the blower operational during
the wash.
6. The total wash cycle duration and the wash duration of each nozzle shall be based upon the correct
programming of the MVT wash cycle timer by the facility safety engineer.
7. Upon completion of the wash cycle, the system shall reset itself to the OFF mode.
8. Refer to MK Plastics programming guide for specific programming information. A detailed ‘Training Guide’
booklet will be included with each timer; this gives information on wiring, istallation and programing.
Fig. 5 – Control Timer
Wiring (TYP.)