Overview
Dissolved Solids
Dissolved solids can precipitate out of solution onto orifice entrance. A ring of precipitation is gradually built up around the orifice. When a portion of this ring eventually breaks and damages the orifice, jet stream quality becomes bad.
Suspended Solids
Particles suspended in water impact orifice edge and can chip it. This results in poor jet quality, poor cutting performance and poor mixing tube life time.
Water requirement
Good Water Quality and Cool Water are Important to Water Jet Systems
Water Quality
Water quality plays important role in life time of certain critical components and water jet quality. The components affected by water quality are jewel orifice, on/off valve, seals, check valves and plunger. High pressure jewel orifice is mostly affected. To achieve high quality cutting, a high quality water jet is required to be created and directed through mixing tube. Any contaminations in the water could cause problems on the jewel orifice.
These contaminates is classified into two groups, dissolved solids and suspended solids.
Water that is too pure also causes problems with high pressure components. Pure water trends to dissolve materials that it comes in contact with. Excessive water treatment is thus, harmful to high pressure components.
A balance should be arrived at between pure water and untreated supply water. Local water supply is recommended to be tested. When supplied water quality is known, adequate water treatment system is then defined. It could be simple filters, a small water softener or, just nothing at all. The cost of water treatment must also be compared to the costs resulting from shortened components life and cutting equipment downtime. If components replacements and downtime comparatively cost lesser than capital investment and operating cost of a water treatment system and, water jet quality is not a major concern, it may rather worthy to go without water treatment.
Water Cooling
Water is warmed up when water is pressurized. When water is pressurized, part of the energy is converted to increase the velocity of the water and rest of energy would heat up the water. The water is hotter and warmed up faster when the high pressure system is installed in where there is no air conditioner especially in tropical areas and/or summer time. The warmer the water, the more wear is found on pumps. If necessary, a chiller system is required to slow down high pressure pump’s wear.
Water Consumption
When cutting at, say, 380 MPa (about 55,000 PSI), water consumptions are,
- 1.9 liters / min. while using 0.25mm orifice,
- 3.1 liters / min. while using 0.33mm orifice,
- 4.7 liters / min. while using 0.40mm orifice.
Water Recycle
Water jet systems consume small amount of water. It is not obviously cost effective if water is recycled.
