How CAT PUMPS Work?

CAT PUMPS are triplex, positive displacement, reciprocating pumps. We offer both the triplex piston and triplex plunger pump styles. With the positive displacement design, each revolution of the crankshaft creates a direct motion in the plunger rods [piston] resulting in a positive output of flow from the pump. This output from the pump [flow] is in direct relation to the RPM of the pump. The bore and stroke determine the amount of liquid handled with each stroke and revolution. The discharge pressure is created by the restriction placed upon the flow through nozzles or restrictions downstream. Our triplex pumps deliver a smooth, constant flow and pressure. These triplex pumps can also be powered by a vari-drive to adjust the flow as needed with changes in demand. The downstream restriction will require adjustment or a valve to regulate the change in flow. The following examples describe how the liquid passes through the various types of CAT PUMPS.

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Piston Pump UNIFLOW Design

The design of the piston pump is for the fluid to move continually in one, smooth forward direction. This design allows greater suction capabilities up to –8.5 PSI and reduced risk of cavitation provided the pump is properly primed.

At the beginning of the stroke, the mechanically actuated inlet valve [and piston] close. As the piston rod moves forward, the liquid is forced out through the discharge valves. Simultaneously, the liquid is entering the pump inlet and flowing in behind the inlet valve.

As the piston rod begins the backward stroke, the inlet valve mechanically opens, permitting the liquid to continue its flow forward through the piston into the discharge chamber, until the stoke is completed.

Note: The spring tension on the discharge valves requires a minimum of 100 PSI discharge pressure to properly activate the valves.

Plunger Pump DIRECT FLOW Design

The spring-reinforced, preset packing design of the plunger pumps permits significantly greater pressures than piston pumps. The plunger pumps also offer tremendous versatility with optional direct coupling drives and wet-end material options.

Like the piston pumps, the design of the plunger pump also allows for forward liquid flow, however, both the inlet and discharge valves are spring-loaded closed and hydraulically opened.

At the beginning of the stroke, the plunger displaces the liquid in the manifold chamber and forces the discharge valve open. There is a split second at the end of the stroke when both inlet and discharge valves are closed.

As the plunger rod begins its backward stroke, the inlet valve opens to allow more liquid into the manifold chamber, thereby keeping a smooth forward flow of liquid.

Note: The spring tension on the discharge valves requires a minimum of 100 PSI discharge pressure to properly activate the vales.

SF Plunger Pump SUPERFLOW Design

The SF plunger pumps are a combination of the UNIFLOW piston and direct flow plunger pump designs. In the SF pumps, both the inlet and discharge valves are spring-loaded closed and hydraulically opened, just like the plunger pumps, however, they have a flow- through ceramic plunger design.

The continuous forward flow characteristic of the piston pumps is utilized in conjunction with the spring-reinforced, preset packing design of the plunger pumps. These features give the SF pumps strong suction capabilities and higher pressure performances.

At the beginning of the stroke, the inlet valve is closed against the ceramic plungers and the flow is forced out through the discharge valves.

As the plunger rod begins its backward stroke, the inlet valve opens [moves away from the ceramic plunger] and allows the inlet flow to enter the manifold chamber through the holes in the ceramic plunger.

Note: The spring tension on the discharge valves requires a minimum of 100 PSI discharge pressure to properly activate the vales.

Flushing Port Design

Select K-models with the Block-Style manifolds and C-models with the cast manifolds are available with a special ported inlet manifold. These Flushed C and K pump models offer unique opportunities for flushing and cooling and control of effluent emissions. This external flushing greatly enhances seal life when pumping low lubricity liquids such as DI water or high temperature liquids.

Special ports in the Inlet Manifold permits a small amount of secondary liquid to pass between the Hi-Pressure Seals or V-Packings and Lo-Pressure Seals. This flush helps cool the seals and minimize the effects of high temperature liquids. The flushing liquid provides added lubrication with low lubricity liquids such as DI water. CAT PUMPS is the exclusive manufacture of flushed pumps for DI water gas turbine inlet fogging. The flushing liquid will also contain any leaking from the seals as they begin to wear to prevent unfriendly liquids from escaping the pump. This inlet manifold flushing is especially helpful with liquids that tend to vaporize.

The secondary flushing liquid is selected to be compatible with the primary pumped liquid and is circulated at a small flow and low pressure. The flushing liquid is typically pumped at a minimum of 5 GPH up to 1 GPM depending upon pump size and pumped liquid characteristics at a nominal 5 PSI.

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