| Do I need a baffled supply tank? |
| A baffled supply tank provides the optimum inlet condition for the pump
when properly sized and fitted. It eliminates entrapped air bubbles or suspended particles from entering the pump and helps assure a consistent inlet liquid supply.
CAT PUMPS generally require flooded to 60 PSI inlet pressure [see individual Data Sheet] with ambient temperature water applications. Above 130
degrees F, a pressurized inlet of 30 PSI is recommended for optimum inlet conditions. If the standard water supply line pressure is above 60 PSI, a pressure reducing valve at the pump inlet is recommended to reduce the line pressure to within pump limits.
When using a supply tank, it is recommended it be sized 6 to 10 times the system capacity [for example…with a 20 GPM pump, the tank should be 120 gal min.] with two baffles secured at the bottom of the tank. This supply tank should be within 5 to 6 feet of the pump with the outlet from the tank slightly above the inlet of the pump. All by-pass and feed lines to the tank should be on the opposite side from that feeding the pump [see view].
These tanks should be in a material suitable to the liquid being pumped. Stainless Steel from a metal fabricator or Polyethylene, typically found at agricultural supply stores, are two of the most common types.
|
|
| What inlet line size should I have? |
| The inlet line size is one of the most critical elements in a system, however, a combination of other factors affect the inlet conditions. Undersized lines, too many elbows and fittings, clogged inlet filters, too many demands on the liquid supply line or an undersized supply tank may result in starvation [restricted inlet flow to the pump].
Flooded inlet from a baffled supply tank that is sized 6-10 times the
system capacity or pressure feeding the pump are the best options.
Make certain the line size is one size larger than the pump inlet port.
Use reinforced flexible hose [to avoid collapsing lines] to and from the pump. Eliminate all harsh elbows. Check and clean filters regularly. Carefully review the facility for total liquid demand before installing a high pressure system. |
|
| What is the maximum negative inlet pressure for a Cat Pump®? |
| The standard piston pumps have a -8.5 psig rating and the plunger pumps have either a -5.0 psig rating on standard models. Various higher rpm models require a flooded inlet. Pumps with a short stroke, higher rpm operation and applications with high-temp liquids, higher vapor points or higher viscosity solutions generally require flooded or pressurized inlet conditions. Contact us with your special liquid to determine the optimum inlet condition.
The mechanically actuated inlet valve and flow through design in the piston pumps permits a slightly higher negative inlet condition than on the plunger pumps, however, liquids other than ambient temperature water should be carefully reviewed. [See individual pump Data Sheet]
When the supply tank or feed line is below the pump inlet, whether it is feeding a single pump, multiple pumps or stacked pumps, you need to be certain you stay within the pump inlet suction limits to assure adequate flow into the pump.
Long feed lines can create water hammering or line losses and may require increasing the line size or adding a booster pump to avoid negative inlet conditions.
As a general guide, 12 feet is equal to -5.0 PSIG and 18 feet is equal to –8.5 PSIG.
Other factors such as line size, undersized supply tank, improperly or non-baffled supply tank, the number of elbows, filters and valves can also affect the delivery of liquid to the pump inlet.
|
|
|
