day tank instrument to avoid oil overflow

in simple way you must have level controlling include monitoring system.but you must know what is the suitable level transmitter which depend in the tank volume eg. for large tanks you can use radar ,ultra-sonic , small tanks you can use electrical floater, after that you can use this signal to control the level through control valve also you can use this signal to set an alarm system to alert operator about the level when level exceeded set value.

also for more safety you can install a level switch which close a shut-off valve when the level get to the maximum level

Since a spill could be very costly, you should really monitor with a device that doesnt touch the material. Then you wouldn't have to clean it often. Like the utlra sonic or radar. When setting up the monitoring, you should have a high high, high, normal, low and maybe low low for points of alarm and control. Your transmitter may have the capabilities of alarm points and control built in. Or just a 4-20 ma output monitoring the level, that you could send to a control processor or PLC with a touch screen to visually see the level at the operators station. Now the whole thing could cost about 20,000, but then an enviromental fine could be more!

Hope that helps.

Since it is mentioned that the intention is only to avoid overflow only some form of on/off control is required meaning that an isolation valve with open/close capabilities (i.e. a solenoid operated valve) will be sufficient.

It is always useful to have continuous monitoring of the level in the tank so a transmitter with some sort of single loop controller or monitor with switch/contact outputs would be required to energize and de-energize the trip solenoid accordingly.

A product called a trip amplifier is sold which will provide the 24vdc to power your transmitter and also has the capability to open and close switch contacts at different values of loop current e.g. open valve at 25% and shut valve at 90%. This has the advantage over a basic switch of not cycling the valve (opening and closing this is also referred to as chattering) if the level bounces around the level of the switch.

A switch can or should still be incorporated as a safety to ensure that the valve is closed in the event of a transmitter or amplifier failure.

Of course the cheapest solution will be to use a switch only but again this may result in the valve closing once the level reaches the switch and opening once the level drops below the level of the switch at which time the tank will be refilled almost immediately.

Guys,

Thanks for your imformative assessment. In some ways, operator's negligence resulted to overflow. On/off switch is at the area. A clear hose was also installed at the side of the tank to determine physically the level of the tank, but if the operator forgot his responsibility overflow has been occured. On this matter i need the instrument, if you have any specification of such it would be a great help.

Best Regards

The simplest instrument would be some form of gauge and someone there to monitor it. As to "best", well, that depends.......

LEVER OPERATED FLOAT VALVE