A micro piston pump for gas sampling should be selected by the flow measured at the analyzer inlet with the final tubing, filter, gas, voltage, and operating cycle installed. Pinmotor's PYP385-XZ provides 5.0–7.0 L/min no-load vacuum flow, which can be used as a starting reference for vacuum sampling systems.

How Stable Should Flow Be in a Gas Sampling System?

Sample flow should remain inside the range required by the analyzer or sensor throughout the measurement period.

Sample flow stability is the ability of the gas circuit to maintain the required inlet flow while the analyzer is operating. A useful specification includes a target flow in L/min, an allowed variation in %, and a fixed test condition.

There is no single flow-stability percentage for every analyzer. Air monitoring devices, gas detectors, laboratory analyzers, and calibration equipment can use different sensor technologies and inlet-flow requirements.

Free-flow pump data is useful for initial model screening. It does not show the actual flow after the pump is connected to tubing, filters, valves, fittings, and the analyzer inlet.

Measure the final flow close to the analyzer inlet. This measurement includes the effect of the complete gas path and shows what the sensing section actually receives.

Keep the following conditions unchanged during comparison tests:

● Tube inner diameter
● Tube length
● Filter type
● Valve configuration
● Gas medium
● Pump voltage
● Measurement point
● Test duration

For compact vacuum sampling circuits, the micro piston vacuum pump for sampling provides a reference for evaluating the required vacuum and inlet-flow condition.

A gas sampling project should define the target inlet flow before pump approval. The flow range should then be checked with the production tubing, filter, voltage, and sample path installed.

Vacuum Sampling or Pressure Feeding: Which Layout Fits?

Vacuum sampling pulls gas from a sampling point toward the analyzer. Pressure feeding pushes gas toward a chamber or controlled inlet.

1、Vacuum Sampling

A vacuum sampling system commonly follows this path:

Sample Point → Filter → Pump → Analyzer

The pump creates negative pressure that moves gas through the sampling line.

Vacuum sampling is commonly used in:

● Air quality monitoring
● Environmental gas detection
● Portable gas analyzers
● Laboratory sampling systems

The main system variables are inlet flow, sampling distance, tube dimensions, filter resistance, vacuum level, and leakage.

Leakage can change the gas mixture entering the analyzer. Outside air entering through a loose fitting or seal may dilute the sample before it reaches the detector.

Measure sample flow at the analyzer inlet after the complete line has been assembled. A measurement taken only at the pump port does not include losses caused by the sampling circuit.

2、Pressure Feeding

A pressure-fed system normally follows this path:

Gas Source → Pump → Valve → Analyzer

This layout is used when gas needs to be pushed toward a calibration chamber or controlled inlet.

Pressure feeding requires its own pressure-flow data. Vacuum performance data should not be used to calculate positive-pressure performance.

If an analyzer uses vacuum draw during measurement and pressure feeding during calibration, define the two modes separately.

For applications that need pump configuration changes around ports, wiring, voltage, or installation layout, custom micro piston pump OEM options can be reviewed before prototype testing.

What Changes Sample Flow After Installation?

1、Tubing, filters, valves, fittings, leakage, supply voltage, and the sampled gas can change the final flow reaching the analyzer.

2、Tube diameter and length affect gas-path resistance. A long tube or a smaller internal diameter can reduce delivered flow compared with an open pump connection.

3、Filters also create resistance. A loaded filter can produce a different pressure drop from a new filter, so the filter condition should be included in the test record.

4、Valves and fittings may contain passages smaller than the connected tubing. A restriction at one fitting can limit sample flow even if the pump still has unused capacity.

5、Voltage should be measured at the pump terminals while the pump is running. Wiring and connector resistance can cause the voltage at the pump to differ from the power-supply setting.

6、Leakage should be checked in vacuum systems. A pump may continue drawing air while a leak allows outside gas to enter the line.

7、The sample medium also matters. Humidity can create condensate, while some gases require specific material compatibility.

If the application requires an oil-free gas path or contact with a specific gas, use product-level material documentation before approving the pump.

For projects where the gas path, mounting layout, or electrical connection needs adaptation, the micro piston pump OEM for sampling page provides the appropriate OEM route for sample evaluation.

How Should a Gas Sampling Pump Be Tested?

Test the pump inside the complete sampling circuit using the production tubing, filter, valve, voltage, and sample medium.

Start by measuring analyzer-inlet flow at the beginning of the test. Use the same flowmeter location for all later readings.

Record the operating cycle, including:

1、Pump ON time
2、Pump OFF time
3、Starts per hour
4、Longest continuous run
5、Pump-terminal voltage
6、Analyzer-inlet flow

Repeat the flow measurement during the operating period and again at the end.

Keep the filter condition and tubing layout unchanged. Changing either variable during testing makes the results harder to compare.

For systems with valve switching, measure flow before and after each valve event. This can identify temporary changes that a single steady-state reading will miss.

A useful acceptance record includes:

● Target inlet flow in L/min
● Allowed flow variation in %
● Test duration
● Tube inner diameter in mm
● Tube length in m
● Filter condition
● Pump-terminal voltage in V
● Sample medium
● Measurement location

The same test condition can then be used for incoming samples, design changes, and later production checks.

Selection Checklist

Use measurable system data before approving a micro piston pump for gas sampling.

1、Set the analyzer inlet flow. Record the target in L/min and the permitted variation in %.

2、Define the sampling mode. Mark the circuit as vacuum sampling or pressure feeding.

3、Measure the tubing. Record the inner diameter in mm and total tube length in m.

4、List the gas-path components. Include filters, valves, moisture traps, fittings, and sensing chambers.

5、Set the pressure condition. Record the required vacuum or pressure in kPa at the relevant point in the circuit.

6、Measure pump voltage. Record the voltage at the pump terminals while the pump is operating.

7、Define the sample medium. Record gas type, humidity condition, and any condensate risk.

8、Set the operating cycle. Record ON time, OFF time, starts per hour, and longest continuous run.

9、Fix the measurement point. Use the same analyzer-inlet position for every flow test.

10、Keep the approved configuration. Record the final pump, tubing, filter, voltage, and measured flow range used for sample approval.

Buyers who also need to review manufacturing capability, model matching, and production support can use the micro piston pump manufacturer page during supplier qualification.

Common Mistakes

1、Using Free-Flow Data as Analyzer Working Flow

Free-flow data describes the pump under low restriction. It does not include the pressure loss created by tubing, filters, valves, and the analyzer inlet.

Use free-flow data for model screening. Use analyzer-inlet flow for final acceptance.

2、Measuring Flow Only at the Pump Port

A pump-port measurement does not include the full gas path.

Use at least two stages during development: pump screening and assembled analyzer testing.

3、Ignoring the Noise Test Condition

385-XZ lists noise at ≤75 dB measured at 30 cm.

The 30 cm distance is part of the published condition and should stay with the number when the specification is quoted.

4、Treating a Life Test as Field Service Life

385-XZ records a continuous life test of at least 500 hours.

The 500-hour test result should remain identified as a test value. It should not be converted into a longer field-service interval without separate application data.

FAQ

1、What flow rate should a gas sampling pump provide?

The required flow is the value specified at the analyzer inlet with the final tubing, filter, gas, voltage, and operating cycle installed. Free-flow pump data can be used for initial screening. Final approval should use a target flow in L/min and an allowed variation in % measured at the analyzer inlet.

2、How stable should sample flow be during analysis?

Sample flow should remain inside the tolerance specified by the analyzer or sensor for the full measurement period. There is no universal percentage for all gas analyzers. Define the target flow, allowed variation, test duration, measurement point, tubing, filter, voltage, and gas condition before pump approval.

3、Is maximum vacuum the same as analyzer working vacuum?

Maximum vacuum is the pump limit under the stated datasheet condition. Analyzer working vacuum is the pressure required while sample gas is moving through the completed circuit. Set the working point from inlet flow, tubing resistance, filter loss, and detector limits, then verify the assembled sampling path.

4、Can one pump be used for vacuum sampling and pressure feeding?

A pump can cover both functions only when separate vacuum and positive-pressure performance data support both operating modes. Vacuum sampling and pressure feeding should have separate flow and pressure acceptance points. Do not use a vacuum specification to estimate positive-pressure performance.

5、Does gas type affect pump selection?

Gas composition, humidity, condensate, and chemical exposure can affect pump material requirements and contamination limits. State the sample medium before pump approval. If the gas can attack seals or create condensate, use product documentation and sample testing that cover the specified gas and operating condition.

6、What information should I send for a gas sampling pump project?

Send the target inlet flow in L/min, allowed variation in %, working vacuum or pressure in kPa, gas type, humidity condition, tubing dimensions, filter details, voltage, operating cycle, and installation space. These values provide a measurable basis for model selection and sample testing.

Last updated: 2026-10-15