TG 240D Portable Helium Leak Detector
One sniffer.
Every tracer gas.
The TG 240D is a pocket-sized helium leak detector that also reads hydrogen, argon, CO₂, SF₆, methane and refrigerants. It pinpoints leaks down to 1 × 10⁻⁵ cc/s — the micro-leaks that soap bubbles and standard refrigerant sniffers walk right past.
What is a helium leak detector?
A helium leak detector finds leaks by tracing helium gas as it escapes from a pressurized system. Helium atoms are tiny, inert and rare in normal air, so they slip through cracks too small for refrigerant oil stains or soap bubbles to reveal — and they're easy to tell apart from the background.
The TG 240D is a handheld sniffer-type helium leak detector. Its probe draws in air around joints and fittings; because helium conducts heat far better than air, the thermal-conductivity cell responds the instant helium arrives, and the reading climbs as you close in on the leak.
Why technicians choose a portable helium leak detector
- Finds micro-leaks other field methods miss
- Tests systems before they're charged with refrigerant
- Inert, non-flammable tracer gas
- Goes anywhere — rooftops, mechanical rooms, MRI suites
- A fraction of the cost of a mass-spectrometer leak detector
Helium leak detector sensitivity — plus every other tracer gas
Most electronic detectors are tuned to one family of gases. Because the TG 240D measures thermal conductivity, it responds to nearly any gas that differs from air — and its unsaturable cell recovers instantly after a big hit instead of going blind.
The chart shows the smallest leak the detector registers for each gas. Longer bar = finer detection.
Other gases on request — ask us.
How to find a leak with a helium leak detector
Charge the system
Pressurize the circuit with helium, argon, or a non-flammable 5% H₂ / 95% N₂ mix — never above the system's rated test pressure.
Warm up & zero
Power on in clean air. The cell heats in about 60 seconds and zeros itself automatically on the ambient atmosphere.
Set gas & range
Select He or Ar calibration, then start on LO to find the general area and step up to MED and HI to close in.
Sniff & confirm
Move the tip slowly along joints. The bar graph climbs and the tone rises as you near the leak; mark it, repair, and re-check.
Engineered for the service van, not the lab bench
Unsaturable sensing cell
A thermal-conductivity cell with active suction gives fast response and clears quickly after a large leak, so you can keep hunting.
OLED bar graph + tone
A progressive graphic ramp and a rising audible signal let you track leak intensity without staring at the screen.
He / Ar selector, 3 ranges
Switch calibration between helium and argon, with HI, MED and LO presets for coarse search and fine pinpointing.
Self-monitoring
Automatic zeroing, ambient-contamination indication, and continuous checks for cell errors and low battery.
Serviceable in the field
Sniffer pipe, spiral cable and detection block swap out directly, and replacement parts are available through H2Leak.
Full-shift battery
Built-in rechargeable pack delivers 6–8 hours and charges overnight from any USB-C source.
Know which way your gas travels
Escaping tracer gas rises or sinks depending on its density compared with air. Position the probe tip where the gas will collect and you'll find leaks faster with fewer false starts. Work in still air when you can — fans and wind scatter the plume.
Helium rises. Sniff just above joints and along the top of runs.
Gas sinks. Sniff below fittings and at low points in the piping.
Helium leak detection for HVAC, refrigeration & MRI service
Faster diagnosis, fewer callbacks
- Locate leaks in coils, condensers and evaporators
- Check brazed joints, Schrader cores and valves
- Prove a repair is tight before recharging
- Commission new installs before startup
Control refrigerant loss on racks
- Supermarket rack systems, walk-ins, display cases
- CO₂ and HFC systems, heat exchangers
- Supports EPA Section 608 leak-repair work
- Aligns with GreenChill leak-reduction goals
Protect costly liquid helium
- Helium fill and transfer-line fittings
- Cold-head and compressor line connections
- Cryostat and dewar leak checks
- Calibrated directly for helium — no conversion
Move past the dunk tank
- Replace bubble testing on the line
- Pinpoint QC failures for targeted rework
- Verify rework before final test
- Reduce scrapped coils
Seal packs before they ship
- Pack and module enclosure seams
- Weld, gasket and adhesive joints
- Thermal-management coolant plates
- Locate leaks for rework, not full rejection
One tool across the plant
- Pressure vessels and process piping
- Vacuum chambers, labs and cleanrooms
- SF₆ switchgear and gas storage
- Pipeline and hydrogen tracer testing
Helium leak detector vs. bubbles and refrigerant sniffers
| Feature | Soap bubbles | Refrigerant sniffer | TG 240D helium leak detector |
|---|---|---|---|
| Finds micro-leaks | Rarely | Sometimes | Down to 1×10⁻⁵ cc/s |
| Works before refrigerant charge | Yes | No | Yes — with tracer gas |
| Gases detected | Any (visual only) | Refrigerants | He, H₂, Ar, CO₂, SF₆, CH₄, refrigerants & more |
| Hard-to-see joints | Difficult | Yes | Yes — flexible probe |
| Graded leak indication | No | Varies | Bar graph + audible ramp |
Helium leak detector specifications
| Detection | Unsaturable thermal-conductivity cell with suction |
|---|---|
| Gases | He, H₂, Ar, CO₂, SF₆, CH₄, refrigerants, O₂, N₂ |
| Helium sensitivity | 1×10⁻⁵ – 1×10⁻² cc/s |
| Calibration | He / Ar selectable; automatic zero on ambient air |
| Display | OLED graphic ramp, audible signal, battery & contamination indication |
| Warm-up / response | ~60 s / ~1 s |
| Battery | Built-in rechargeable, 6–8 h; ~12 h full charge via USB-C |
| Probe | Calibrated flexible pipe with protective tip; spiral cable, 1 m relaxed |
| Housing | Shockproof plastic, 22 × 5 × 4 cm, 0.350 kg |
| Operating range | 10–40 °C; not explosion-proof |
Sensitivity presets
Leak rate that drives the bar graph to 100% in each position.
| Range | Helium | Argon |
|---|---|---|
| HI | 5×10⁻⁵ cc/s | 3×10⁻⁴ cc/s |
| MED | 1×10⁻⁴ cc/s | 5×10⁻⁴ cc/s |
| LO | 1×10⁻³ cc/s | 5×10⁻³ cc/s |
In the case
- TG 240D helium leak detector with built-in battery
- USB-C charger
- Rugged transport case
- User manual
How does a helium leak detector work?
The system is filled with helium, then the detector's probe draws in air around joints and fittings. Helium conducts heat far better than air, so when escaping helium reaches the TG 240D's thermal-conductivity cell the reading jumps, and the bar graph and audible tone rise as you get closer to the leak.
How sensitive is the TG 240D helium leak detector?
The TG 240D detects helium and hydrogen leaks as small as 1×10⁻⁵ cc/s, argon down to 5×10⁻⁵ cc/s, and refrigerant gases down to 3×10⁻⁵ cc/s.
Helium or hydrogen — which tracer gas should I use?
Both read at 1×10⁻⁵ cc/s on the TG 240D. Helium is inert and the detector is calibrated for it directly. A 5% hydrogen / 95% nitrogen mix is typically less expensive and easier to source, and is non-flammable. Many contractors keep both on hand.
How is a portable helium sniffer different from a mass spectrometer leak detector?
Mass spectrometer helium leak detectors reach far lower leak rates but are large, costly and usually used in labs or on production lines. A handheld thermal-conductivity helium leak detector like the TG 240D goes anywhere, costs far less, and is sensitive enough for HVAC, refrigeration, MRI and most industrial service work.
Can it find refrigerant leaks without a tracer gas?
Yes. Refrigerant gases are detectable down to 3×10⁻⁵ cc/s, so you can sniff a charged system directly. Tracer gas is the choice when the system is open, evacuated, or newly installed.
Is it suitable for MRI and cryogenic helium work?
Helium is the TG 240D's primary calibration gas, which makes it a natural fit for checking fill lines, fittings, cryostats and dewars where lost helium is expensive.
How long does the battery last?
6–8 hours per charge, a full working shift. A complete recharge takes about 12 hours over USB-C, so an overnight charge has you ready the next morning.
Can it be used in hazardous locations?
No. The TG 240D is not explosion-proof and must not be used in hazardous or explosive atmospheres.
Stop guessing. Start pinpointing.
Get helium leak detector pricing, fleet discounts for your service team, or a live demo from H2Leak.
