Testing a filter means comparing particle counts upstream and downstream, not reading a single mass concentration number. The instrument has to count particles in size channels, hold a stable flow, and log enough data to show a before and after. These six handheld counters are the ones in this batch that genuinely do that job.
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This comparison was built from the supplied product listings only. Every specification quoted appears in the listing bullets for that product. Where a listing does not publish a figure, the table and the review say so rather than estimating.
Seven simultaneous channels, ISO 21501-4 calibration, and 2M+ record logging.
Same seven-channel PMD331 platform with USB export and a 4-inch screen.
Six size channels, stated 2.83 L/min flow, and 2M+ records at a lower position.
Pump suction, three size channels, and temperature and humidity alongside.
Three fine channels plus mass concentrations and a stated 4-hour battery.
Three channels by count, PM2.5 and PM10 by mass, with an audible limit alarm.
No pick matches that combination yet. Try a wider budget or a different measurement.
| Pick | Size channels | Sampling flow | Data storage | Calibration stated | Export | |
|---|---|---|---|---|---|---|
| 7 channels: 0.3, 0.5, 0.7, 1.0, 2.5, 5.0, 10 um | Not stated in the listing bullets | Up to 2,000,000 records | ISO 21501-4 | RS485 Modbus | View | |
| 7 channels: 0.3, 0.5, 0.7, 1, 2.5, 5, 10 um | Not stated in the listing bullets | Up to 2,000,000 records | ISO 21501 and NIST | USB flash drive or RS-232 Modbus | View | |
| 6 channels: 0.3, 0.5, 1.0, 3.0, 5.0, 10 um plus PM2.5 and PM10 | 2.83 L/min (0.1 CFM) | More than 2 million records | Not stated in the listing bullets | USB Type-C | View | |
| 3 channels: 0.3, 0.5, 1.0 um plus PM2.5, PM10, TSP | Not stated in the listing bullets | Not stated in the listing bullets | Not stated in the listing bullets | Not stated in the listing bullets | View | |
| 3 channels: 0.3, 0.5, 1.0 um plus PM2.5, PM10, TSP | Not stated in the listing bullets | Not stated in the listing bullets | Not stated in the listing bullets | Not stated in the listing bullets | View | |
| 3 channels: 0.3, 2.5, 10 um plus PM2.5 and PM10 | Not stated in the listing bullets | Not stated in the listing bullets | Not stated in the listing bullets | Not stated in the listing bullets | View |
Cells show only what the supplied listing bullets state. Where a listing is silent, the cell reads Not stated. P3 and P4 describe the same PMD331 platform, so their table rows are near-identical by design.
The right choice depends on whether you are screening a filter or certifying one, and on how many size channels you need to see the fraction you care about.
If you need to see coarse-fraction removal, you need channels at 3, 5 and 10 micrometres. If you only care about fine breakthrough, three fine channels can be enough.
A stated flow rate in litres per minute lets you convert counts to a concentration. Without it, you can only compare counts relatively.
A filter test is two runs, upstream and downstream. Pick a unit with enough storage to log both without overwriting.
If the test result has to stand up to a client or an auditor, the listing should state a calibration standard and supply a certificate.
A user-set concentration alarm is a convenience, not a safety device. It does not certify air as safe to breathe.
A walkthrough of several rooms needs hours of runtime. A single filter test can be done in minutes, so battery life matters less.
Mass concentration collapses all particle sizes into one number weighted by mass, so a few large particles dominate it. A filter's performance changes with size: it may catch 10 micrometre particles well and 0.3 micrometre particles poorly. Counting per channel shows that split; mass concentration hides it.
A filter rating describes the fraction of particles in a defined size range that the filter removes under a standard test. It is not a promise about your ductwork, your airflow, or the seal around the filter. A rated filter installed with a bypass gap will test badly, which is exactly what an upstream and downstream count comparison reveals.
Yes, for relative comparison. You can measure upstream, measure downstream, and look at the ratio of counts. You cannot convert those counts into a concentration per cubic metre, because you do not know how much air was sampled.
For routine filter checks, no. For a test result that has to be traceable, such as a cleanroom certification or a contractual filter efficiency claim, yes. The calibration standard is what makes the count defensible.
Sample at the same flow, for the same duration, at ports that are as close as possible to the filter face on each side. Take several samples at each port and average them, because particle counts fluctuate. Then compare the two averages channel by channel.
No. A particle counter measures particles; it does not detect carbon monoxide, combustible gas, or oxygen deficiency, and it does not certify air as safe to breathe. A concentration alarm on a counter is a convenience feature, not a safety certification.
The PMD331 is the only unit in this batch whose listing publishes a full seven-channel size split. For filter testing that matters because a filter's job changes with particle size: a coarse pre-filter removes the 5 and 10 micrometre fraction while letting the 0.3 micrometre fraction through, and a high-efficiency final filter does the opposite. If your counter only reports PM2.5 mass, you cannot see that split. Seven channels let you watch each size band upstream and downstream and see which one the filter is actually catching.
The listing states ISO 21501-4 compliance and says every unit is calibrated, which is the standard that governs how a light-scattering particle counter is calibrated against a reference. That is the claim you want on a unit used for filter efficiency work, because an uncalibrated counter can drift and make a good filter look bad. The stated German Furgut pump and Parker filters are there to hold flow steady; a counter that samples at a wandering flow rate will report wandering counts even when the air is unchanged.
The RS485 Modbus output and 2,000,000-record storage are the practical features for HVAC work. You can log a long upstream and downstream run, export it, and compare the two traces rather than trusting a single spot reading. The listing does not publish the sampling flow rate in litres per minute, so you cannot calculate a cleanroom classification from it without that figure; ask the seller before relying on it for ISO 14644 work.
This is the same PMD331 platform as P3, described with a different transfer option and a larger stated screen. The listing here names both ISO 21501 and NIST compliance and says a calibration certificate accompanies every unit, which is the document an HVAC contractor hands over when a client asks for proof the filter test was done with a traceable instrument. The 4-inch screen and per-channel selection mean you can watch one size band at a time while you move the probe from the upstream port to the downstream port.
The mechanism is the same as any light-scattering counter: a laser illuminates the sample stream, particles scatter light, and a photodetector counts pulses and sorts them by amplitude into size bins. The value of the PMD331 for filter work is that it sorts into seven bins at once, so a single sample tells you the whole size distribution rather than one slice of it. Data transfer by USB flash drive is the simplest route for a technician who wants to hand a file to a client without installing software.
Because P3 and P4 describe the same instrument, the honest advice is to choose on availability and on which transfer method you need, not on any claimed performance difference. The listing does not state the sampling flow rate, so you cannot derive a particles-per-cubic-metre concentration from a raw count without it; the unit reports counts, and the listing does not publish the volume sampled per minute.
The JD-3000 is the value pick because it publishes the one number the premium units leave out: a sampling flow of 2.83 L/min, which is 0.1 cubic feet per minute. That figure is the standard flow for handheld airborne particle counters, and it is what lets you convert a raw particle count into a concentration per unit volume. Without a stated flow, a count is just a count; with it, you can compare two rooms or two filter states on equal terms.
The six size channels cover the range that matters for HVAC filters. The 0.3 and 0.5 micrometre channels show what a high-efficiency filter is catching, while the 3.0, 5.0 and 10 micrometre channels show what a coarse pre-filter is catching. The listing also displays PM2.5 and PM10 mass concentrations alongside the counts, which is useful for a quick client-facing number even though mass concentration is the wrong metric for filter efficiency testing.
The 2 million record storage and USB Type-C export are the practical features. A filter test is a before-and-after comparison, so you need to log a baseline, change or clean the filter, then log again, and export both runs. The listing does not state a calibration standard, so treat the counts as relative rather than traceable; for filter efficiency work, relative counts upstream and downstream are often enough, but for certification you need a calibrated unit.
The Temtop pump-suction unit is a screening tool rather than a certification instrument. It publishes three size channels, 0.3, 0.5 and 1.0 micrometres, which are the fine end of the range. That is the right end for checking whether a high-efficiency filter is passing fine particles, but it will not tell you how much of the 3, 5 or 10 micrometre fraction is getting through a pre-filter. If your filter test is about fine particle breakthrough, three channels can be enough.
The pump suction matters because it draws a controlled sample rather than relying on a fan or diffusion. A pump gives a more consistent sample volume, which makes upstream and downstream comparison more repeatable. The listing states temperature and humidity sensors are integrated, which is useful context: humidity affects some particle counters because hygroscopic particles grow in damp air and read as larger than they are.
The listing does not state the sampling flow rate, the calibration standard, or the battery life, so you cannot convert counts to a per-volume concentration or claim traceability. Treat it as a relative comparison tool: measure upstream, measure downstream, and look at the ratio. For a homeowner or a technician doing a quick filter check, that is often all that is needed.
This Temtop unit is the simplest instrument in the batch. It counts at 0.3, 0.5 and 1.0 micrometres and reports mass concentrations for PM2.5, PM10 and TSP. For filter testing, the three fine channels are the ones that show whether a high-efficiency filter is doing its job, and the mass concentrations give a familiar number for a report. It does not publish channels at 3, 5 or 10 micrometres, so it cannot show coarse-fraction removal.
The listing states a 3500 mAh battery good for over four hours of continuous monitoring. That is the practical figure for a walkthrough: long enough to sample several rooms or several filter stages without recharging. The temperature and humidity sensors are there to flag conditions that affect readings, particularly humidity, which can change how particles scatter light.
The listing does not state the sampling flow rate or a calibration standard, so the counts are relative. For a homeowner checking whether a filter change made a difference, relative counts before and after are enough. For a contractor signing off on a filter efficiency claim, they are not. The unit is best understood as a screening monitor that happens to count particles, not a certification-grade counter.
The FTVOGUE unit is unusual in this batch because it counts in three channels but two of them, 2.5 and 10 micrometres, are the same sizes used for the PM2.5 and PM10 mass figures. That means the count channels and the mass channels are not independent; they describe the same size bands in two different units. For filter testing, the 0.3 micrometre channel is the useful one for fine particle breakthrough, and the 2.5 and 10 micrometre channels show the coarser fraction.
The listing states an internal pump for active sampling at constant flow, which is the right mechanism for repeatable upstream and downstream comparison. It also offers continuous and single-sample modes, with the single sample stated at 180 seconds. A 180-second sample is a long integration, which smooths out short fluctuations and gives a more stable number for a filter test.
The audible alarm is set by the user and triggers when concentrations exceed the limit. That is useful for a walkthrough where you want to know when you have found a leak or a bypass, but it is not a substitute for logging. The listing does not state the sampling flow rate or a calibration standard, so the counts remain relative.
Short answer: For HVAC filter testing, the two Temtop PMD331 listings (P3 and P4) are the strongest picks because they publish seven simultaneous size channels, a stated ISO 21501-4 calibration, and large internal data storage, which is what you need to compare upstream and downstream counts. The JD-3000 (P5) and its duplicate listing (P8) are the value pick: six size channels, a stated 2.83 L/min flow, and over two million records of storage. The Temtop pump-suction unit (P2) and the Temtop handheld (P1) are useful for walkthrough screening but publish fewer channels. The YWBL-WH (P6), FTVOGUE (P7), Jiawu (P9), and SENECESLI (P10) are lower-cost options with three to six channels; the Fluke 985 (P11) belongs here but its listing publishes almost no specifications. The NasalGuard gel (P12) is not an instrument and was excluded.
A particle counter and a PM2.5 monitor are not the same instrument, even when they sit in the same housing. A mass monitor reports micrograms per cubic metre, which is a weight-based figure. A particle counter reports how many particles it saw in each size band, usually as counts per litre or counts per cubic foot. For filter testing, the count is the more useful number, because a filter’s job is to remove particles of particular sizes, not to reduce a single mass figure.
The reason mass concentration misleads is that mass scales with the cube of diameter. One 10 micrometre particle weighs about a thousand times as much as one 1 micrometre particle. So a mass reading is dominated by the largest particles present, and a filter that removes the coarse fraction will look excellent on mass even if it is passing every fine particle. If you are testing a high-efficiency filter, the fine fraction is the one you care about, and only a per-channel count shows it. For a wider look at the category, see our particle counter buying guide.
The mechanism behind the count is light scattering. A laser illuminates a thin stream of sampled air. Each particle crossing the beam scatters light, and a photodetector turns that flash into an electrical pulse. The height of the pulse scales with particle size, so the instrument can sort pulses into bins. That is why a counter with more bins gives you a finer picture: seven channels separate the size distribution into seven slices, while three channels merge everything into three.
A filter test is not a single reading. It is two readings, one taken before the filter and one after, compared channel by channel. The upstream sample tells you what is arriving at the filter. The downstream sample tells you what got through. The ratio between them, per size channel, is the filter’s efficiency for that size band.
To make that comparison fair, both samples have to be taken the same way. Same flow rate, same duration, same distance from the filter face, and ideally several samples at each port averaged together. Particle counts fluctuate naturally, so a single spot reading on each side can be misleading. A unit with large internal storage makes this easy: log a run upstream, log a run downstream, export both, and compare. The JD-3000 (P5) and the two PMD331 units (P3 and P4) all publish storage in the millions of records, which is more than enough for a full filter survey.
The common mistake is to sample at the wrong place. A reading taken at a supply grille tells you about the air in the room, not about the filter. A reading taken at a return grille tells you about the room again. To test the filter itself, you need ports immediately upstream and immediately downstream of the filter media, which usually means drilling test ports into the duct or using existing access points. If you cannot get to both sides of the filter, you are not testing the filter; you are testing the room. Our differential pressure meter guide covers the companion measurement, because pressure drop across a loaded filter is the other half of the picture.
A filter rating such as MERV or a HEPA class is a laboratory result. It describes how the filter performed in a standard test rig, at a standard face velocity, against a standard challenge aerosol. It is a useful starting point, but it is not a prediction of what the filter will do in your system. Real installations have bypass gaps around the frame, uneven loading, and airflow that differs from the test condition.
That is why field testing exists. A filter that carries a high rating but is installed with a gap at one corner will show a downstream count that is barely lower than the upstream count for the size band that the gap passes. A counter with channels at 3, 5 and 10 micrometres will catch that, because coarse particles slip through gaps more readily than fine ones. A counter with only fine channels may miss it. This is the practical argument for more channels: not certification, but fault-finding.
It is also worth knowing that a filter’s efficiency changes as it loads. A new filter and a loaded filter of the same rating do not behave identically, and some filters become more efficient as they collect a dust cake. If you are comparing a filter’s performance over time, you need to log the same measurement at intervals, which again points to a unit with real storage. For related indoor air work, our air particle monitor guide covers the screening end of the market.
A raw particle count is only half a measurement. To turn it into a concentration, you need to know how much air was sampled. That is why the sampling flow rate matters. The JD-3000 (P5) publishes 2.83 litres per minute, which is 0.1 cubic feet per minute, the standard handheld flow. With that figure you can convert a count into particles per litre or per cubic foot and compare two locations on equal terms. Without it, as with the Temtop PMD331 listings (P3 and P4), the Temtop pump unit (P2), the Temtop handheld (P1) and the FTVOGUE (P7), you can only compare counts relatively.
Calibration is the other number that makes a count defensible. The PMD331 listings state ISO 21501-4 compliance and, in the P4 listing, NIST compliance with a certificate supplied with every unit. ISO 21501-4 is the standard that governs how a light-scattering particle counter is calibrated and how its counting efficiency is verified. A unit without a stated calibration standard can still be useful for relative before-and-after work, but its absolute counts should not be presented as traceable.
One more practical point: humidity. Many particles, including some dusts and salts, absorb water and grow in damp air. A particle that was 0.5 micrometres in dry air can read as 1 micrometre in humid air, which shifts counts between channels. Units that publish temperature and humidity sensors, such as the Temtop handheld (P1) and the Temtop pump unit (P2), let you note the conditions alongside the count. If you are testing filters in a humid basement or a kitchen, that context matters. Our basement air quality monitor guide covers the damp-air problem in more detail.
A handheld counter is a screening and fault-finding instrument. It is not a certification instrument unless it is calibrated to a recognised standard and used within a controlled procedure. If you need to certify a cleanroom to ISO 14644, you need a calibrated counter with a known flow rate, a documented sampling plan, and a defined number of sample locations and volumes. A handheld unit with no stated flow rate cannot do that, no matter how many channels it has.
It is also not a safety device. A particle counter does not detect carbon monoxide, combustible gas, or oxygen deficiency, and it does not tell you whether air is safe to breathe. If you are working in a confined space or around combustion, you need a gas detector, and our confined space gas detector guide covers that separate category. A concentration alarm on a particle counter is a convenience for spotting a sudden change, not a safety certification.
Finally, a particle counter is not always the right first purchase for a filter problem. If the complaint is that a room feels stuffy, the cause may be inadequate fresh air rather than filtration, and a CO2 monitor will show that faster and cheaper. If the complaint is that a filter is loading too quickly, a differential pressure meter across the filter tells you more about the loading than a particle count does. Buy the counter when the question is specifically about what size of particle is getting through, and buy it with enough channels to answer that question.
This comparison was built from the supplied product listings only. Every specification quoted appears in the listing bullets for that product. Where a listing does not publish a figure, the table and the review say so rather than estimating. Products that do not belong to the topic were excluded: the NasalGuard gel (P12) is a topical barrier product, not an instrument, and the Fluke 985 (P11) was excluded from the picks because its listing publishes almost no specifications beyond three application phrases, leaving nothing to compare. The JD-3000 appears twice in the supplied data, as P5 and P8, with identical bullets; only P5 is written up, and P8 is noted as a duplicate. The YWBL-WH (P6), Jiawu (P9) and SENECESLI (P10) were also excluded from the picks because their listings overlap heavily with the units already covered and add no new stated specification. No laboratory testing was performed and no measurements of our own are published.
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