MK Plastics Venturi IO&M - Manual (Page 5)

5
The 3-Way Solenoid Valves
These valves are 3-way, diaphragm operated, solenoid pilot controlled. They are made of brass with only four moving
parts: a core assembly, two diaphragm assemblies, and a disc holder sub-assembly.
Normally Closed – see Fig. 6
Solenoid De-energized: Flow is from cylinder ‘A’ to exhaust ‘E’. Pressure ‘P’ connection is closed.
Solenoid Energized: Flow is from pressure ‘P’ to cylinder ‘A’. Exhaust ‘E’ connection is closed.
The valve is designed to perform properly when mounted in any position. However, for optimum life and performance,
the solenoid should be mounted vertically and upright to reduce the possibility of foreign matter accumulating in the
solenoid base sub-assembly area. The flow direction and pipe connection of the valves are indicated on the body;
pipe connections have to be in accordance with the size indicated on the nameplate and fitted accordingly. To protect
the solenoid valves, install a strainer or filter at the inlet side as close to the valve as possible.
Clean the valves periodically; in general, if the voltage to the solenoid is correct, sluggish valve operation, excessive
noise, or leakage will indicate that cleaning is required. Clean valve strainer or filter when cleaning the valve. Causes
of improper operation are as follows –
1. Incorrect Pressure: check valve pressure, the pressure to the valve must be within the range specified on
the nameplate. Pressure recommended for the Venturi washing is stated on the submittal, and may vary
depending on a particular job.
2. Excessive Leakage: Disassemble the valve and clean all parts. Replace worn or damaged parts.
Fig. 6 – 3-Way Solenoid Valve Flow Diagram
Operation and Maintenance Instructions
1. The blower must be in operation when perchloric acid exhaust hood is being utilized.
2. Program the timer to open the solenoid valves for the duration as required by the facility safety engineer. Set
washing intervals as often as necessary depending on the frequency of use of the perchloric acid hood by
examining for sediments at the back of the hood.
3. Connect the heater strip at the bottom of the Venturi to the 120-volt – 0.5A electrical supply. It must be on a
different circuit than the disconnect switch. The heater comes with a thermostat, which is built in and
maintenance free. The heater strip, (or cable), remains wrapped around the washing ring water pipe all year
round, but it is recommended disconnecting the power at the end of the season when the temperature
remains above 50ºF. The thermostat turns the cable on when exposed to temperatures below 38ºF. It will
shut off when the pipe has been heated to 45ºF. At the end of the cable, bottom of venturi stack, is a
standard electrical plug for an outlet. We strongly recommend the use of a GFCI protected circuit and not to
overload the outlet. If an extension cord is necessary, use only a properly sized, grounded, CSA/UL Certified
cord suitable for outdoor service.
4. Water to the washing ring/nozzle must be made available and a pressure gauge installed to assure sufficient
pressure and flow.
5. At start of system read the pressure gauge on the water pipe to confirm that it agrees with MK Plastics
specifications.
6. Verify at set periods that the wash controller is operational and functioning properly.
7. The disposal of the perchloric acid washing liquid must be done according to municipal codes and
regulations governing polluting containments.
3-Way Solenoid Valve