20
06
Operation
Manual 1843 Rev B p/n 001843 0000
When gas ballast is used, the ultimate pump
pressure increases, more oil mist is created in the
pump discharge and power consumption increases
slightly (within the standard motor rating). Pump
noise can be generally eliminated by using a small
flow of gas ballast with only a slight increase in
ultimate pump pressure.
Continuous use of gas ballast is recommended
where the process pressure requirements can be
met with the gas ballast valve open; otherwise,
intermittent use of gas ballast between process
cycles is suggested. If use of gas ballast at neither
of these times is tolerable, it is advisable to run the
pump using full gas ballast when process work is
not being done, such as overnight.
Use the gas ballast valve as follows:
1.
CONTINUOUS GAS BALLAST —
With the
pump operating, open the gas ballast valve
until the ultimate pressure is slightly below that
needed for the process. Operate the pump in
this manner continuously to aid in preventing
oil contamination and to minimize noise.
2.
INTERMITTENT GAS BALLAST DURING
PROCESSING —
With the pump operating,
fully open the gas ballast valve during periods
when this will not affect the process (work
preparation, recycling, etc.). This will aid in
cleaning the oil.
3.
CONTINUOUS GAS BALLAST WHEN NOT
PROCESSING —
With the pump operating
but isolated from the process, fully open the
gas ballast valve. If convenient, operate the
pump overnight in this manner to clean badly
contaminated oil. Gas ballast will remove vapor
contamination but will not remove solids such
as varnish. If it is necessary to clean the oil
using gas ballast in the short period, the time
needed can be estimated as follows: With the
pump inlet blanked-off, open the gas ballast
valve fully and operate the pump for a short
period (15 to 20 minutes). Close the gas ballast
valve and observe the pressure change after
1 to 2 minutes of running. Use the “pressure
change versus time” as a rough guide to
estimate the total time required to obtain the
desired blank-off pressure.
STALLING
If the pump stalls at any time, it may be due to
foreign contamination, loose belts, or lack of
lubrication caused by failure of the oil circulating
pump, badly contaminated oil, coating build-up,
or foreign matter in the pump or oil line strainer
(KT-500 and KT-850). If the pump cannot be turned
over freely by hand after cooling, there is foreign
matter in the pump and the inside of the pump
must be cleaned.
Sometimes a process-related coating build-up can
be removed by soaking the pump with the proper
solvent (while turning by hand).
See Disassembly
on page 29
for information on inspecting the
inside of the pump. Tuthill Vacuum and Blower
Systems is able to clean and recondition KT pumps
through its factory repair department and network
of Authorized Service Centers.
PUMP LEAKS
If the pump is suspected of having an air leak, after
eliminating oil contamination as the cause of poor
performance, use a plastic sealing compound to
seal over suspected areas (check carefully around
housing joints, pipe connections, plugs, oil lines,
and any other penetrations into the vacuum area)
and check pump blank-off performance before
making permanent repairs with Loctite 515. If
gasketed connections are suspected, remake the
connections. Plastic sealing compound may be
used to make temporary gaskets; these should
not be made too thick since the material may be
squeezed into the pump. Check the shaft seal for
mechanical defects, such as a cracked carbon
washer or hardened rubber components.
For checking leaks, a fast-acting total pressure
gauge used with acetone or a sensitive helium leak
detector can be used. A helium leak detector is the
most convenient to use, if available.
