Most tube mill central coolant pumps do not provide sufficient
clean coolant to properly cool impeders, particularly return flow
types & impeders used with ID scarfing mandrels.
EHE's coolant booster pumps & filtration systems consist of
turbine type pressure boost pumps mounted on a welded steel
frame, with dual stainless steel filters, a filter selection valve,
pressure flow & filter condition gauges, temperature gauge and
a pressure regulator.
Magnetic particle skimmers and refrigerated chillers are
available as optional extras. Additional flow, pressure &
temperature monitoring & interlocks can also be provided.
The coolant system has 1Ó male NPT or BSP connections for coolant inlet & outlet. Either clean city water or mill coolant is connected to the upper pipe nipple or flange on the rear of the unit. (see above). The pressurized & filtered coolant is discharged through the lower pipe nipple or flange.
The turbine pump is driven by a 3 phase, 60Hz., 230/460 volt motor. Motors are normally supplied wired for 230 volts. These pumps should not be run dry. Coolant should be flowing through the system before power is applied to the motor. A directional arrow on the motor casing indicates correct rotation. Pump motors are drip proof but should be kept reasonably dry.
The pump is normally wired in such a manner that it is on any time the welder is operating. Turbine pumps are intended for high pressure, relatively low volume applications such as impeder cooling. Standard single stage centrifugal pumps do not provide sufficient pressure for this application.
Use of a well designed impeder cooling system allows the ferrite in the impeders to operate at a lower temperature. This increases its operating life and efficiency so that less welder power can be used for the same production speed. Savings in electrical power alone will pay for a pump & filtration system in less than 6 months. (Based upon a 10% saving in power on a 200kW welder operating 80 hours/week.)
The pump is designed to boost the pressure of the coolant by up to 120 PSI. Most impeders are tested at 120 PSI & this is the maximum recommended operating pressure. If the mill central coolant system, or the city water supply provides 80 PSI, the operation of the booster pump will raise this by up to 120 PSI, for a maximum of 200 PSI. Since this is above the recommended operating pressure for most impeders, a bypass valve is provided to vary the amount of boost pressure applied. This should be adjusted to a maximum of 120 PSI for each different impeder size or type that is used.
Filter Operation & Maintenance
The filter canisters are normally provided with 100 mesh stainless steel filter cartridges. These are washable & do not normally require replacement. A twin circuit, two way valve is used to select either left or right filter. The deselected filter may be removed for cleaning without interrupting the coolant supply. The valve handle always points toward the operating filter, so if the handle is to the left, the right hand filter can be removed.
Before removing the filter canister, drain any trapped coolant using the drain cock at the bottom of the canister. Care should be exercised when draining the right hand filter to ensure that coolant does not enter the motor. When re-installing the filter cartridge, make sure that the rubber seals are properly seated in the filter housing, to avoid damage to the seals.
If a filter cartridge is damaged, replacements are available from EHE. Please order using part number 9.75-100-PBS-DOE.
In coolant systems that are heavily contaminated with mill scale and/or metallic fines, more frequent filter cooling will be required. A filter condition indicator is attached to the front side of the unit. When the needle moves into the yellow zone, the filter should be cleaned. Filter cleaning intervals can be greatly extended by installing an EHE magnetic skimmer ahead of the dual filters. This continuously removes any magnetic particles from the coolant before it enters the booster pump/dual filter system.
Use of a properly maintained impeder coolant system will greatly extend the operating life of most types of impeders, thereby reducing down time & improving mill productivity.