Temtop PMD 331 vs PMD 351 vs PMD 371: Particle Count, Aerosol Mass or Both?

A cleanroom engineer asks for a particle counter. An EHS officer asks for a PM2.5 and PM10 dust monitor. A maintenance team wants to understand why an air filter is allowing more particles into a production area.

All three may be discussing airborne contamination, but they are not necessarily asking for the same measurement.

That is the key to choosing between the Temtop PMD 331, PMD 351 and PMD 371. The instruments use laser light scattering, but the information they report is different. Buying the model with the most measurement channels is not always the right decision. First, establish whether your application needs a particle number count, an aerosol mass concentration or both.

Particle Count and Aerosol Mass: What Is the Difference?

A particle counter reports the number of airborne particles detected at specified particle sizes. Its readings help you understand particle contamination in a sampled volume of air. This is particularly useful when investigating cleanroom conditions, particle generation and filtration performance.

An aerosol mass monitor reports an estimated concentration of suspended particles by mass, commonly in µg/m³ (micrograms per cubic metre). Measurements such as PM1, PM2.5, PM4 and PM10 are more useful when a requirement is expressed as particulate mass concentration.

These readings cannot be treated as interchangeable. A cloud of very fine particles can contain a large number of particles without necessarily having the same mass as a smaller number of larger particles. Particle number tells you how many were detected; mass concentration estimates how much particulate material is present per volume of air.

The PMD 371 is intended for situations where both views are needed.

Temtop PMD 331 vs PMD 351 vs PMD 371: Quick Comparison

All three models are listed with a 4-inch TFT LCD, rechargeable battery, approximately eight hours of operation, USB/RS485 communication and onboard data storage. Before planning a control-system connection, confirm the exact interface and protocol of the supplied instrument.

Temtop PMD 331: When Particle Number Matters Most

Imagine a pharmaceutical production area where the maintenance team has replaced an air filter. The question is not simply whether the PM2.5 mass concentration has changed. They may need to examine how the number of airborne particles changes at specific sizes before and after maintenance.

This is the type of investigation where the Temtop PMD 331 Particle Counter makes sense.

Best for: Teams whose monitoring requirement is expressed as particle counts rather than particulate mass.

Why this model makes sense: The PMD 331 reports seven particle size channels, from 0.3 µm to 10 µm. This gives an engineer more useful particle size information than a single overall dust reading. Its selectable 3 to 60 second sampling period can also be practical for short checks at multiple locations.

Technical points to note:

• Seven reported particle sizes: 0.3, 0.5, 0.7, 1, 2.5, 5 and 10 µm

• Particle number measurement range up to 3,000,000 particles/ft³

• Quoted particle number accuracy of ±10% with calibration aerosols

• Nominal sampling airflow of 2.83 L/min

• Laser light scattering measurement principle

• Selectable sampling time from 3 to 60 seconds

• Manufacturer brochure states ISO 21501 compliance

Where it is commonly considered: Pharmaceutical manufacturing areas, electronics assembly, controlled environments, air filtration investigations, cleanroom maintenance checks and particle contamination studies.

Selection caution: Do not choose the PMD 331 when the customer specifically needs PM2.5 or PM10 in µg/m³. Also, cleanroom classification or formal HEPA integrity testing requires the applicable procedure and verified instrument calibration, not simply a particle count displayed on the screen.

Temtop PMD 351: When Aerosol Mass Is the Requirement

Consider an industrial workshop where cutting, material handling or nearby production activity generates airborne dust. The EHS or facility team wants to compare particulate conditions at different locations, especially using PM2.5 and PM10 values.

For that requirement, the Temtop PMD 351 Aerosol Monitor is the more direct choice.

Best for: Industrial dust surveys and general air quality investigations where the required result is particulate mass concentration in µg/m³.

Why this model makes sense: Instead of displaying the seven particle count channels, the PMD 351 reports five aerosol mass metrics: PM1, PM2.5, PM4, PM10 and TSP. The display is easier to align with a monitoring requirement that already specifies a PM mass metric.

Technical points to note:

• Five displayed mass metrics: PM1, PM2.5, PM4, PM10 and TSP

• Mass concentration resolution of 0.1 µg/m³

• Quoted accuracy of ±10% under calibration aerosol conditions

• Nominal sampling airflow of 2.83 L/min

• Laser light scattering measurement principle

• Sampling time of 60 seconds

• Rechargeable battery and handheld design

Where it is commonly considered: Factory dust investigations, industrial HVAC surveys, ventilation performance checks, warehouses, indoor air quality investigations and site-to-site PM comparisons.

Selection caution: Optical aerosol instruments estimate mass from light scattering. Actual readings can be affected by dust composition, particle shape and moisture. Do not automatically treat a handheld optical reading as equivalent to a reference gravimetric test or a prescribed occupational exposure compliance measurement. Also confirm the mass measurement range for the version being supplied.

Temtop PMD 371: When Particle Count and Aerosol Mass Are Both Needed

Some investigations do not fit neatly into a particle counter or a mass monitor category. Suppose a manufacturing facility has recurring airborne contamination. The quality team is concerned about the number of particles reaching a sensitive process, while the facility team wants PM2.5 and PM10 trends to evaluate the overall dust condition.

Using two separate instruments may be inconvenient. The Temtop PMD 371 Particle & Aerosol Monitor combines the two sets of readings in one handheld unit.

Best for: Cross-functional air contamination investigations where engineers need both particle number and aerosol mass information.

Why this model makes sense: The PMD 371 reports the same seven particle size channels associated with the PMD 331 and the five PM mass metrics associated with the PMD 351. An investigator can therefore review particle count and PM concentration during the same monitoring exercise without switching between different instrument categories.

Technical points to note:

• Seven particle counting sizes: 0.3, 0.5, 0.7, 1, 2.5, 5 and 10 µm

• Five mass metrics: PM1, PM2.5, PM4, PM10 and TSP

• Particle number range up to 3,000,000 particles/ft³

• Mass concentration range from 0 to 9,999.9 µg/m³

• Mass concentration resolution of 0.1 µg/m³

• Nominal sampling airflow of 2.83 L/min

• Selectable sampling periods of 1 to 60 minutes

• Manufacturer brochure states ISO 21501 compliance for particle counting

Where it is commonly considered: Pharma and electronics facilities, manufacturing contamination investigations, clean production areas, filtration studies, HVAC performance assessments and technical air quality surveys.

Selection caution: The quoted ±10% particle number accuracy should not be assumed to apply to every PM mass output. Check the applicable accuracy specification for each measured parameter. The PMD 371 is also not automatically the better purchase when the customer needs only one measurement type.

Which Temtop Model Fits Your Application?

What to Confirm Before Buying

The mistake many buyers make is selecting a dust monitor by the model name, display appearance or number of channels alone. A better approach is to clarify what the engineer will do with the readings.

1. Identify the reporting unit. Does the requirement specify particle counts or µg/m³?

2. Confirm particle sizes or PM metrics. For example, 0.3 µm particle counts are not the same output as PM2.5 mass concentration.

3. Check sampling time. A short site check and a longer investigation may need different sampling settings.

4. Ask about calibration. Confirm the calibration certificate, date, aerosols used and any relevant compliance requirements.

5. Confirm communication. USB/RS485 availability does not by itself confirm a particular PLC, SCADA or Modbus implementation.

6. Review the operating environment. High dust loadings, humidity and aerosol characteristics can affect the suitability of an optical instrument.

7. Define the purpose of the test. Troubleshooting, trending, cleanroom classification and statutory compliance do not have identical instrument requirements.

Common Selection Mistakes

Why Buy Temtop Particle Monitoring Instruments from Radical TechMart

At Radical TechMart, product selection begins with the measurement requirement, not just a part number.

A purchase inquiry for an “air particle monitor” may actually refer to cleanroom particle counting, industrial PM concentration measurement or a combined investigation. Those are different applications, and identifying the distinction early helps prevent a costly mismatch.

Our team can help you compare the Temtop PMD 331, PMD 351 and PMD 371 based on the reported parameters, sampling requirement, application, available specifications and commercial requirements.

Final Thoughts

The Temtop PMD 331 is the logical starting point when your requirement is to count airborne particles at defined sizes. The PMD 351 is more appropriate when you need aerosol mass information such as PM2.5, PM10 and TSP. The PMD 371 brings both measurement types together for investigations that need a broader picture.

Before ordering, ask one practical question: What measurement does the final report or maintenance decision actually require? Once that is clear, choosing the right Temtop model becomes much easier.

Frequently Asked Questions

1. What is the main difference between Temtop PMD 331 and PMD 351?

The PMD 331 reports particle number across seven size channels. The PMD 351 reports aerosol mass metrics such as PM1, PM2.5, PM4, PM10 and TSP in µg/m³.

2. Does Temtop PMD 331 measure PM2.5 mass concentration?

The PMD 331 specification does not list PM2.5 mass concentration as an output. It lists a 2.5 µm particle counting channel, which is a different measurement.

3. Is Temtop PMD 371 better than PMD 331?

Not for every application. PMD 371 offers both particle number and mass reporting, while PMD 331 is a more focused choice when only particle counting is needed.

4. Which Temtop model should I use for PM10 dust monitoring?

Consider PMD 351 when you need PM10 mass concentration. Choose PMD 371 if your investigation also requires particle counting.

5. Can I use PMD 331 or PMD 371 for cleanroom testing?

Their brochures state ISO 21501 compliance for particle counting. For formal cleanroom classification, confirm instrument calibration, required sampling procedure and suitability under the applicable cleanroom standard before testing.

6. Can these instruments connect to a PLC or SCADA system?

The supplied brochures list USB/RS485 communication. Verify the actual communication protocol, data format and model configuration before specifying PLC or SCADA integration.

7. Does the PMD 371 measure dust mass directly?

No. It uses laser light scattering and reports estimated aerosol mass concentration. It does not replace a gravimetric laboratory measurement simply because it displays µg/m³.