Evaporation Losses

Dear Editor, What as a percentage would be regarded as "average" water evaporation losses. eg: On a centralized system of 20,000L of conventional MWF with 10-12 machines and constant outside/inside temp of 25?C (80?F). Can anyone suggest from their experience what the evaporation losses from this type of system (or any other large 20,000-100,000 L centralized system) would be? VA
Filed Under: 
Maintenance / Condition Monitoring

Anonymous (not verified)

Fri, 2011-03-11 15:12

Dear VA The rate of evaporation of water is relatively slow.  It depends on several factors, including temperature, pressure, humidity, surface area (not volume), and air circulation at the surface.  Turbulent water circulation will increase the rate of evaporation by increasing the surface area.  Any real engineer (excluding the proposed Texas definition) will be able to provide you with a calculation based on your specific environmental measurements, but the calculations are somewhat complex and won't account for drag out, circulation turbulence, and surface air movement.  You can estimate it easier yourself by placing a large pan next to the tank and measuring the loss - assuming you can trust the machinist not to mess with you. The Editor

Anonymous (not verified)

Fri, 2011-03-11 15:12

Dear VA A very good question and a difficult one to answer.  Here is why: 1 You mention 10 to 12 machines, what operations are these machines performing milling, turning,   broaching grinding?  Each of these operations will have a different evaporation rate and drag out rate.  If you were to mix these operations well that changes things too. 2. You mention 20,000 Liters what size pumps, what type of system configuration, what type of filtration once again all these things contribute to your question and it's answer. 3. You mention standard metalworking fluid.  Std. Soluble Oil, Semi-synthetic, Synthetic, or Solution Synthetic, once again different fluids different evaporation rates. As you can see your question has no easy or pat answer rather the answer depends on many parameters. I once said these systems are alive cause each one has a different personality, so the truly answer your question you must determine the evaporation rates using the techniques I describe for concentration control and keep good records and that is the best answer I can give you.  Good luck Dom