Article Summary

A practical guide to micro piston pump pressure and vacuum selection. Learn how to compare working pressure, airflow, vacuum level and pump-down time instead of choosing a pump from maximum ratings alone.

Micro Piston Pump Pressure Guide: How Much Pressure or Vacuum Do You Need?

A micro piston pump should be selected from the pressure or vacuum required during normal operation, not only from the maximum values on a datasheet. Airflow changes as the load increases, and tubing, filters, valves and chamber size can also affect the final result. The useful number is the pump performance at the actual working point.

Micro Piston Pump Pressure Selection at a Glance

Before comparing pump models, define the real pneumatic requirement of the equipment.

● Confirm the required working pressure or target vacuum.
● Check the airflow available at that operating point.
● Do not combine maximum flow with maximum pressure.
● Include the resistance created by tubing, filters and valves.
● Test the pump in the same air circuit planned for production.

1. Working Pressure vs Maximum Pressure

Maximum pressure shows the upper pressure capability of a pump. Working pressure is the pressure the equipment needs while the pump is still supplying the required airflow.

These two values should not be treated as the same thing.

For example, a datasheet may show a maximum flow of 10 L/min and a maximum pressure of 100 kPa. This does not mean the pump can deliver 10 L/min at 100 kPa.

If the equipment actually needs 4 L/min at 80 kPa, then the useful selection point is 4 L/min at 80 kPa.

A high maximum pressure number does not automatically make a pump suitable. The pump still needs to provide enough airflow at the required pressure.

For projects that need different piston pump configurations, refer to the micro piston pump pressure and vacuum options.

2. Read Pressure and Flow Together

As pressure increases, the airflow available from a micro piston pump usually changes.

This is why pressure and flow should be checked at the same operating point.

Suppose an OEM project requires 5 L/min at 60 kPa. A pump rated at 8 L/min maximum flow may still be unsuitable if its airflow falls to 3 L/min when the pressure reaches 60 kPa.

The pressure-flow curve is therefore more useful than the maximum flow number by itself.

A simple curve normally contains three useful areas:

Free Flow → Working Point → Maximum Pressure

Free flow is measured with little system resistance. The working point is where the equipment actually operates. Maximum pressure is the upper pressure endpoint.

For pump selection, the working point is the value that matters.

Tubing diameter, tube length, filters, valves, fittings and nozzles can all increase resistance. These parts should be included when checking the final airflow.

3. How Much Vacuum Does the System Need?

Vacuum selection follows the same rule.

A pump should not be selected only because its specification shows -70 kPa or -80 kPa.

The target vacuum needs to be checked together with airflow and, for a sealed chamber, evacuation time.

For example, two systems may both require -70 kPa. One may have a very small chamber and allow 10 seconds to reach the target. Another may have a much larger chamber and need to reach -70 kPa within 3 seconds.

The vacuum number is the same, but the pump requirement is different.

For vacuum applications, the useful question is not only:

How much vacuum can the pump reach?

The better question is:

How quickly can the pump reach the required vacuum in my system?

A compact -70 kPa micro piston vacuum pump may work well for one chamber but be too slow for another. The chamber volume, tubing and leakage should be tested together.

4. Compare Pressure and Vacuum by Working Condition

There is no need to force every piston pump into fixed pressure classes.

The application requirement can be used directly.

A positive-pressure application may need moderate pressure but relatively high airflow. A vacuum application may need a stronger final vacuum but only a small amount of continuous airflow.

This is why a pump with the highest pressure or vacuum value is not always the better choice.

For larger piston-pump platforms, a 12V/24V piston air pump can be checked against the required operating point rather than selected from voltage or product name alone.

5. Test the Pump in the Real System

A pump can perform differently after it is installed in the equipment.

During prototype testing, use the same tubing length and diameter, filters, valves, fittings and chamber volume planned for production.

These parts affect the pneumatic resistance and can change the final pressure, vacuum and airflow.

For positive-pressure applications, record the airflow while the pump is operating at the required pressure.

For vacuum applications, record both the target vacuum and the time required to reach it.

An open-port test can confirm basic pump performance, but it does not reproduce the resistance inside the finished equipment.

If the project also needs to compare voltage, motor type or operating cycle, see the micro piston pump selection guide.

Frequently Asked Questions

1、Is 1 bar equal to 100 kPa?

Yes. For normal pump selection, 1 bar equals 100 kPa. For example, 0.5 bar is 50 kPa and 0.8 bar is 80 kPa.

2、Is maximum pressure the same as working pressure?

No. Maximum pressure is the upper capability limit of the pump. Working pressure is the pressure the equipment must maintain while the required airflow is still available.

3、Can maximum flow and maximum pressure occur at the same time?

Normally no. Maximum flow and maximum pressure are different points on the pump performance curve.

4、Is -80 kPa always better than -70 kPa?

No. If the equipment only needs -60 or -70 kPa, airflow and pump-down time may be more useful than a higher maximum vacuum rating.

5、What is more important for vacuum: kPa or airflow?

Both matter. Vacuum shows how much negative pressure the pump can reach. Airflow affects how quickly air is removed from the system.

6、What information should I provide for pump selection?

Provide the required working pressure or vacuum, airflow, chamber volume if applicable, target evacuation time, voltage, operating cycle and basic tubing information.

Send Your Working Point

Send Pinmotor the required working pressure or vacuum, airflow, chamber volume, voltage and operating cycle. If the application uses a sealed chamber, also provide the target vacuum and required evacuation time.These values can be used to narrow the pump range before prototype testing.