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Old 28-10-2007, 09:07 PM   #191
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Originally Posted by Spakase View Post
Come back to basics. Atom, the solenoid valve and the ORP controller, how does it work?
Very simple. Since the tank is using sump, the flow to the denitrator via siphoning from the tank. A solenoid valve (always off type) is installed between them. The orp controller is used for activating the solenoid.

Example:

1. ORP controller is set at -200mV

2. Once ORP or redox value hit -201mV or below, the controller will supply power to the solenoid.

3. Once solenoid received power, it will open the valve. Siphoning will begin and output of denitrator will flow.

4. Once ORP or redox value hit -199mV, the controller will shut the power. Without power, solenoid will close the valve. Siphoning stop and thus no output from denitrator.
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Old 28-10-2007, 09:11 PM   #192
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Will there be a situation when ORP goes further down and even to -300mV without auto shut off of the valve?
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Old 28-10-2007, 09:16 PM   #193
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Will there be a situation when ORP goes further down and even to -300mV without auto shut off of the valve?
At -200 to -500mV, the valve will remain open.
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Old 28-10-2007, 09:19 PM   #194
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So if you do not monitor and let it go beyond -300mV, the fishes would be in big danger?

What would cause ORP to go below -300mV, you mentioned it reads the presence of reducers, is it the slow flow rate?
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Old 28-10-2007, 09:40 PM   #195
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So if you do not monitor and let it go beyond -300mV, the fishes would be in big danger?

What would cause ORP to go below -300mV, you mentioned it reads the presence of reducers, is it the slow flow rate?
If the denitrator is not choke or the output flowrate not too low (dependent on the size of denitrator), you will not get -300mV or below. This the due to the rich DO tank water entering the denitrator which is high in ORP value.

If it does go below -300mV, the hydrogen sulfide will be produced and nitrate will not be reduced (not totally yet). It is very toxic, a great reducer but very unstable. It reacts readily with the presence of oxygen and oxidised back to sulphate again. In view of this, it is highly recommended to aerate strongly the output from the denitrator. This is meant for:

- to oxidise hydrogen sulfide if any
- to introduce DO back to the anoxic water.
- to oxidise NO2 to NO3 if any. (works best if O3 is used)
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Old 28-10-2007, 10:10 PM   #196
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Quote:
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So if you do not monitor and let it go beyond -300mV, the fishes would be in big danger?

What would cause ORP to go below -300mV, you mentioned it reads the presence of reducers, is it the slow flow rate?
almost impossible unless output is restricted or choked.

the last time it hit -310mV was due to electricial supply tripped while i was at work. once i restart the supply, took around 10mins for value to hit -199mV and solenoid closed.

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Old 28-10-2007, 10:14 PM   #197
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the last time it hit -310mV was due to electricial supply tripped while i was at work. once i restart the supply, took around 10mins for value to hit -199mV and solenoid closed.
when it tripped, was the valve closed?
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Old 28-10-2007, 10:19 PM   #198
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when it tripped, was the valve closed?
The solenoid valve is a magnetic actuated spring loaded type. When no power, the spring will push the piston to shut the valve. When power is provided, the electromagnet will be activated and pull the piston and thus open the valve.

This means that whenever there is a power trip, the valve will not be open. Totally safe.......unless the valve cannot be close properly.
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Old 28-10-2007, 10:33 PM   #199
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when it tripped, was the valve closed?
it's an always close valve thus need electricity to open the valve. totally safe.

Quote:
Originally Posted by atom View Post
The solenoid valve is a magnetic actuated spring loaded type. When no power, the spring will push the piston to shut the valve. When power is provided, the electromagnet will be activated and pull the piston and thus open the valve.

This means that whenever there is a power trip, the valve will not be open. Totally safe.......unless the valve cannot be close properly.
lucky valve can close properly, if not i can have a great time mopping house. should be about 250litres of water only lah
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Old 28-10-2007, 10:48 PM   #200
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lucky valve can close properly, if not i can have a great time mopping house. should be about 250litres of water only lah
You can minimise the mishap by placing the inlet tube inside tank near to the surface.
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