I am designing a liquid dispensing system for CNC machines that will top-up a mixed solution of coolant & water at the required concentration.
Present concentration in the machine sump will almost always be richer than required, so I need to 'dose' the makeup liquid at a concentration of 2-3% to balance the concentration in the sump.
Water will be supplied under gravity through the plant's service line while the coolant shall be pumped from a barrel. I don't know if infeed of coolant can be automated as well since I've been trying to work on this for a while now and have not been able to come up with any viable solutions.
I have done received some data from clients wherein I have concluded the following :-
- Daily top-up is done once in the morning (start of the first shift).
- Top-up volumes range from 20-50 Litres.
So a daily top-up of 20-50 Litres @ concentration of 2-3% is what is required. Water flowing under gravity has to be mixed in-line with the coolant and the mixed solution supplied to the tank through a hose. I cannot have an intermediate mixing tank as there is severe crux for space, so the mixing has to be done in the pipes.
I have thought about using an Injection Quill to inject the coolant concentrate into the water pipe, but i am not sure if it will help.
Also, a dosing pump will dose in pulses, while the water flow is continuous. Can I get the right mixing efficiency in such a case?
Will Hall-Effect Turbine flow sensors be accurate enough for such an application to sense the flow-rate?
Are there any compact motorized valves I can use to throttle the flow of water?
I am planning to use a Capacitive Level Transmitter inserted into the tank to know the volume of liquid present and how much will be required.
The present concentration in the tank shall be fed into the HMI by the user. The PLC will then actuate the process with these parameters viz. makeup volume and concentration.
If someone can guide me as to how I can incorporate all this into a workable solution, I'd be forever grateful.