By Sue Roberts, Contributing Editor
Editor’s Note: This article originally appeared in the October
2015 edition of CIM-Canadian Industrial Machinery.
Waterjet components are sensitive. Feed them with water that is not too dirty, not oo clean, not too warm, but just right, and
they reciprocate with more cutting hours between
maintenance cycles, which equals more profit.
Running just-right process water through the di-rect-drive or intensifier pump extends equipment
and seal life; reduces maintenance and downtime;
and ensures a tight, efficient cutting flow (see
It’s not that tap water is always too dirty. Some
OEMs go by this rule of thumb: If you can drink it,
you cut with it. But water from a city supply or a well
might prevent the touchy high-pressure seals and
lines, seat and poppet valves, plungers, and other
critical parts from working together to make you the
Tanner Coker, an OMAX® Corp. engineer specializing in water treatment, said that using “designer
water” that meets the recommended chemical specifications significantly adds to the number of operating hours between maintenance shutdowns.
“Once you tear into a pump and the systems to
do a rebuild, you’ve lost 45 minutes of production.
Depending on what’s needed, you can easily lose
a couple more hours before you’re cutting again,”
Coker said. “So it’s good to focus on water treatment
and use designer water if needed as proactive main-
According to John Frosheiser, sales manager at
Pumps & Systems Inc., seal life depends on water
quality and temperature.
“If you have great water quality, but it is hot, you
Too Important to Ignore
are going to get terrible seal life. If you have terrible
water, but it is cold, you are going to get terrible
seal life. The best water you can send to a waterjet
pump is ice-cold and properly treated. It can give
you 1,000 hours of seal life regardless of incoming
Unchecked, heat from the hydraulics and the am-
bient temperature of the shop will kick up the water
temperature. A chiller should keep the water con-
sistently below 60 degrees F, never letting it top 70
degrees F, to protect seals.
Waterjet systems incorporate filters as a last chance
to remove impurities. The dirtier the water reaching those filters, the more frequently they become
clogged and need to be replaced. These filters are
expensive, and so is the downtime to swap them out.
Adding a prefilter kit to purify the water before
it gets to the onboard filter can be an economical
investment. Source water will be run through multiple filters arranged from largest to smallest.
“Filters on the prefilter will be rated at 5 or maybe
10 microns larger than the ones onboard,” Coker
said. “The bigger particles of dirt get caught in the
bigger filters, which are less expensive to replace.
That allows the high-quality, smaller filters to last
longer. A 1⁄2-micron filter may cost a few hundred
dollars, and a 5-micron filter might be around $20.”
Absolute filters, though more expensive than
their nominal counterparts, will block particles to
their micron rating from installation. A nominal filter begins filtering at a higher level and works down
to its rating. For example, when first installed, a
1-micron-rated nominal filter might function at the
20-micron level, but as it collects residue, it will filter down to 10-, then 5-, then a 1-micron level.
Know Your Water Quality
Jim Fields, national sales manager for TECHNI Waterjet™, agreed that however it is achieved, water
quality is critical.
“Before we put water through a pump at a new installation, we look at the water’s alkalinity, silica level, totally dissolved solids [TDS], and the hardness
of the water [see Figure 2]. The equipment components and their seal life depend on that quality.
PAYS OFF IN
The better the water,
the longer the life of
tubes and seals
Process water with a properly balanced chemistry will extend the life of seals and metal components as well as the
time between maintenance downtime. Photo courtesy of TECHNI Waterjet.