The GEM5000 is a handheld landfill gas analyzer that reads methane, carbon dioxide and oxygen, plus static and differential pressure, and calculates balance gas, flow and calorific value from them. Landfill operators use it at the wellhead to tune a gas collection system: take a reading, adjust the valve, read again. It is not the "GEM 5000" blood gas analyzer that shares its name in search results.
What is the GEM5000, and which "GEM 5000" are you looking for?
It is a portable landfill gas analyzer made by LANDTEC and distributed by QED, designed for gas extraction systems, flares and subsurface migration probes. Search results for "gem 5000" are split with an unrelated hospital point-of-care blood gas analyzer. ERE does not sell that one.
ERE lists the GEM5000 Series as a single "Portable LFG Analyzer" variant. The manual describes it as the GA5000 with added flow and calorific-value functions, and the unit can be switched between GEM5000 (extraction monitor) and GA5000 (gas analyzer) modes from its Special Action menu. If you only need gas concentrations, the Geotech GA5000 covers that; for biogas digesters the QED BIOGAS 5000 is the sibling model. Our landfill gas monitoring equipment guide compares all three.
What does the GEM5000 measure and calculate?
It measures CH4, CO2 and O2 directly and reads pressure; flow, balance gas and energy content are calculated. The ranges and typical accuracies below come from the manufacturer's datasheet (accuracy is typical after calibration as the manual recommends).
| Parameter | Range | Typical accuracy | Method |
|---|---|---|---|
| Methane (CH4) | 0 to 100% vol | ±0.3% (0 to 5%), ±0.5% (0 to 70%), ±1.5% FS (70 to 100%) | Dual-wavelength infrared cell with reference channel |
| Carbon dioxide (CO2) | 0 to 100% vol | ±0.3% (0 to 5%), ±0.5% (0 to 60%), ±1.5% FS (60 to 100%) | Dual-wavelength infrared cell with reference channel |
| Oxygen (O2) | 0 to 25% vol | ±1.0% vol | Internal electrochemical cell |
| Static pressure | ±100 in. H2O (±250 mbar) | Resolution 0.01 in. H2O | Direct measurement |
| Differential pressure | Used for flow devices | Resolution 0.001 in. H2O | Direct measurement |
| CO and H2S | 0 to 2,000 ppm and 0 to 500 ppm | ±2.0% FS | Plus models only |
Other datasheet figures: operating temperature -10 °C to +50 °C, 0 to 95% relative humidity non-condensing, a pump flow of typically 550 cc/min (about 80 cc/min against an 80 in. H2O vacuum), roughly 8 hours of battery life and about 4 hours to recharge. It is certified intrinsically safe (ATEX II 2G Ex ib IIA T1 Gb; CSA Ex ib IIA T1) and calibrated to ISO/IEC 17025, with a 3-year warranty and an annual factory service recommended. The CO and H2S cells are listed for Plus models only; ask us to confirm the configuration before you order.
How do you read balance gas and residual N2?
Balance gas is whatever is left after CH4, CO2 and O2 are subtracted from 100%, and residual N2 removes the nitrogen that would normally ride in with the measured oxygen. The manual gives the formulas: Balance = 100% − (CH4% + CO2% + O2%), and Residual N2 = Balance − (O2% × 3.76), where 3.76 is the ratio of nitrogen to oxygen in ambient air (79/21). The analyzer lets you display either Balance or Residual N2.
A worked example (ours, arithmetic only)
| Well | CH4 % | CO2 % | O2 % | Balance % | Residual N2 % |
|---|---|---|---|---|---|
| A | 52.0 | 41.0 | 0.4 | 6.6 | 5.1 |
| B | 38.0 | 30.0 | 6.0 | 26.0 | 3.4 |
| C | 55.0 | 40.0 | 0.2 | 4.8 | 4.0 |
These readings are invented to show the arithmetic. Well B is the one to look at: with 6% oxygen, about 22.6 points of its 26% balance are nitrogen that would arrive with that air, so most of the dilution looks like air ingress rather than a different gas. That is a common way to read the numbers, and your site's gas-quality targets and tuning plan decide what to do about it. The U.S. EPA notes that collection system operators "tune" or adjust the wellfield to improve collection; its landfill gas overview describes vertical wells connected by lateral piping to a header, with a blower or vacuum system pulling the gas.
How do you measure landfill gas flow with a GEM5000?
You attach a flow device; the analyzer itself does not measure flow. QED's manual lists a pitot tube, an orifice plate, an Accu-Flo or an anemometer, plus an optional temperature probe so borehole temperature is recorded with the reading. The analyzer records the initial and the adjusted flow rate for each borehole, which is how a site engineer shows what a valve change did.
- Pitot tube: seat it in the monitoring point with the tip facing into the gas flow, centred and parallel with the pipe, about half way down it. Pressure is read in mbar and high flow is calculated in m³/hr.
- Orifice plate: QED recommends it as good practice because the fixed method makes flow measurement repeatable.
- Anemometer: can display m/s and m³/hr. The manual says to take the gas reading first, then the flow reading.
Display units are selectable: flow in scfm or m³/hr, pressure in mbar or in. H2O, temperature in °C or °F, and energy in kW or BTU. ERE does not list pitot tubes or orifice plates as separate products, so ask for a quote if you need them with the analyzer.
How to take a wellhead reading
- Zero the analyzer in clean air at the start of the day's monitoring.
- Fit a clean, dry water trap and the sample tubing; the manual says to always use the water trap.
- Seat the flow device in the sampling point, tip into the flow.
- Run the sample pump, read the gas composition and record the initial flow.
- Adjust the valve if your tuning plan calls for it and record the adjusted flow.
- Purge with clean air before moving to the next well.
How often should you zero and span a GEM5000?
QED's manual says zero at the start of each day's monitoring, and gives two starting points for checks against known gas: a calibration check every week or every other week for a daily monitoring round, or a fresh-air calibration before each session with a span calibration every 4 to 6 weeks. It tells you to let your own calibration history drive the frequency, and to have the analyzer serviced and calibrated by QED by the due date shown on the instrument.
- Regulate calibration gas down to below 200 mbar if you are not using a Landtec regulator, and use a pressure relief valve.
- Pick a span mixture close to the levels you are measuring. For gas migration on a closed landfill the manual suggests 5% CH4 / 5% CO2.
- Log every calibration result so you can see whether the interval should be shorter or longer.
Our instrument calibration services guide covers when to send an instrument out instead of checking it yourself.
What throws off GEM5000 readings?
Water, heat, hydrogen sulphide and other hydrocarbons are the usual culprits, and the manual addresses each.
- Water: always use the water trap; if it floods, change the filter and clear every tube before reuse.
- Heat: carry the analyzer in the vehicle's interior, not the trunk or truck bed, and keep it off hot extraction pipe. A temperature rise can cause erroneous readings.
- Hydrogen sulphide: H2S can push a CO reading up. An external H2S filter removes the effect, but the manual says not to use it on every borehole and to lengthen the sample and air-purge times because it slows the response.
- Other hydrocarbons: ethane, propane or butane in the sample make the methane reading read high, never low, and the effect is non-linear.
- Pressurised exhaust: if the exhaust is connected to a pressurised system, gas flows out of the inlet port.
Does the GEM5000 satisfy Canada's Landfill Methane Regulations?
Not on its own. The federal Landfill Methane Regulations apply to landfills that took municipal solid waste after January 1, 2010 and hold more than 450,000 tonnes in place, or took more than 20,000 tonnes in 2025 or later and hold more than 200,000 tonnes. Open landfills above 664 tonnes of methane generation and closed ones above 1,000 tonnes carry the control obligations, which start in 2028, 2029 or 2035 depending on size and whether a recovery system already exists.
Those obligations include no venting of landfill gas, limits on methane concentration at the landfill surface with regular monitoring, monitoring of equipment and wellfields to find leaks, and an annual report due June 1. A GEM5000 helps with wellfield gas quality, pressure and flow at the wellhead. Surface methane limits are a separate measurement. Environment and Climate Change Canada publishes a technical guidance document on the monitoring methods the Regulations require; check it against your own protocol before you choose instruments. We have not verified which method the Regulations name for each task, so do not read this article as a compliance determination.
Should you buy or rent a GEM5000?
Rent for a one-off verification or a single-season campaign; buy if your staff run wellfield rounds every month. That split is our judgement, not a rule, and it depends on how many wells you visit and how often. ERE offers the GEM5000 for sale and rental, so tell us the number of wells, the visit frequency and whether you need a pitot tube or orifice plate. Our instrument rental guide explains how the rental program works.
Need a landfill gas analyzer for your wellfield?
ERE Inc. has supplied environmental field equipment to Canadian consultants and operators for 30+ years. Tell us the number of wells and what you need to measure, and we will confirm the GEM5000 configuration and accessories.
→ Request a Quote | 1-888-287-EREC | Browse Landfill Monitors | sales@ereinc.com
Frequently Asked Questions
Is the GEM5000 the same as the GEM Premier 5000?
No. The GEM5000 is a LANDTEC landfill gas analyzer. The GEM Premier 5000 is a hospital blood gas analyzer made by a different company.
What gases does the GEM5000 measure?
Methane, carbon dioxide and oxygen, with static and differential pressure. CO and H2S are available on Plus models only, and flow, balance gas and calorific value are calculated.
Can the GEM5000 measure flow without an extra device?
No. It needs a flow device such as a pitot tube, orifice plate, Accu-Flo or anemometer, and an optional temperature probe for borehole temperature.
How often should a GEM5000 be zeroed?
QED's manual says to zero it at the start of each day's monitoring, with a span calibration typically every 4 to 6 weeks and a factory service annually.
Related articles
- Landfill gas monitoring equipment: a buyer's guide for Canadian facilities
- Instrument calibration services: what Canadian facilities need to know
- Environmental instrument rental in Canada: what to rent and when to buy
Lire en français : Analyseur de gaz d'enfouissement GEM5000 : guide d'équilibrage du champ de puits au Canada