Catch it before the slab pours. Keep it tight long after.
The DXH-240 gives contractors one tool for two jobs: pressure-testing new refrigeration piping before it's charged with refrigerant on big-box and grocery builds, and running the annual leak checks that keep existing stores under EPA's leak-rate thresholds.
New systems start clean. Existing ones drift. Both cost your customer money to ignore.
Supermarket rack systems and big-box refrigeration run hundreds of feet of copper, hundreds of brazed joints, and dozens of valves and gaskets. Whether it's a system going in for the first time or one that's been running for years, an undetected leak is the same problem on a different timeline.
Catch it before it's buried
More sensitive than a standard pressure-decay test when tracer gas is used to check new refrigeration piping before it's charged with refrigerant — while a re-braze still costs minutes, not a slab cut or a ceiling tear-out.
Catch it before the compliance clock runs out
Industry estimates put annual refrigerant loss at many grocery stores in the 15–25% range — and under EPA's updated rules, that loss is now a compliance problem your customer can't ignore.
Full-charge threshold that now triggers federal leak-repair rules for HFC and HFC-blend systems under 40 CFR Part 84, effective January 1, 2026 — down from the old 50-lb line.
Annual leak rate that trips mandatory repair for commercial refrigeration equipment — walk-ins, reach-ins, and supermarket racks.
Window your customer has to complete the repair and pass a follow-up verification test once a system is found over its leak-rate threshold.
Cumulative annual refrigerant loss that makes a system a "chronic leaker," reportable to the EPA by March 1 of the following year.
Why hydrogen finds what a soap bottle misses
Tracer gas needs a clean, empty line. On a new piping run there's nothing to recover — you evacuate straight to vacuum and charge with tracer gas. On an existing system, refrigerant has to come out first: recover the existing charge, then evacuate and charge with a blend of 5% hydrogen and 95% nitrogen, sometimes called forming gas. Either way, nitrogen alone can't be sensed, so the hydrogen fraction does the work: it's the smallest, lightest molecule available, small enough to escape through micro-leak paths that refrigerant molecules pass through far more slowly.
At 5% concentration, the mixture is non-flammable — hydrogen won't sustain combustion in nitrogen until it reaches roughly 5.7%, so there's a real margin built in. The DXH-240's sniffer tip picks up that hydrogen at the joint, with a graduated display and a rising tone as you close in on the leak. Once the survey is done, the tracer gas simply vents — no reclaim step required — and the circuit gets evacuated and recharged with refrigerant.
Two jobs, two sequences — same tool
Refrigerant and tracer gas can't be in the circuit at the same time, so the starting point is different for a new build versus an existing system — here's how each one runs.
Before the first refrigerant charge
Evacuate
Pull the new piping network to vacuum to clear air and moisture before any gas goes in — there's no refrigerant to recover on a system that's never been charged.
Charge with tracer gas
Charge the network with 5% H₂ / 95% N₂ to test pressure — typically around 75 psi (500 kPa), or per the line set's design spec.
Pressurize & soak
Hold pressure so the tracer gas reaches every braze, header connection, and valve across the new run.
Scan every joint
Sweep the DXH-240's sniffer tip along every field-run braze and connection before ceilings close in or a slab gets poured over it.
Pinpoint & repair
Any leak found gets re-brazed and re-scanned on the spot, while it's still open and accessible.
Evacuate & charge with refrigerant
Once the network passes, vent the tracer gas, pull a final vacuum, and give the system its first refrigerant charge — clean from day one.
On a system that's already running
Recover refrigerant
Pull the existing charge from the isolated circuit with your recovery equipment and reclaim it — nothing gets vented to atmosphere.
Evacuate
Pull the empty circuit to vacuum to clear residual refrigerant vapor, air, and moisture before any tracer gas goes in, so your reading comes back clean.
Charge with tracer gas
Charge the circuit with 5% H₂ / 95% N₂ to roughly 75 psi (500 kPa) — enough pressure to push gas through even the smallest leak paths.
Pressurize & soak
Hold pressure so the tracer gas has time to migrate to every braze, flare, valve stem, and gasket on the circuit.
Scan every joint
Run the sniffer tip close along every joint, weld, coil return, and case connection, with a slow 360° sweep around each suspected fitting.
Pinpoint & log
Watch the graduated display and listen for the rising tone — log the ppm reading against the exact location.
Repair, evacuate & recharge
After repair, vent the tracer gas, pull the circuit back to vacuum, and recharge with refrigerant to spec. A final scan confirms the leak is closed.
DXH-240 at a glance
A handheld sniffer built for close-contact leak checks on HVAC, refrigeration, and automotive A/C systems.
Sniffer sensitivity for the H2/N2 tracer mixture — roughly equivalent to a 1 gram/year refrigerant leak.
Sensitivity settings let you dial in from a coarse first pass down to fine pinpointing on a single fitting.
Graduated display and a rising tone as the sniffer tip closes in on hydrogen concentration — no need to watch the screen the whole time.
Calibrates against ambient background gas so readings stay accurate from one job site to the next.
Where contractors put the DXH-240 to work
Refrigerant and tracer gas can't be in the circuit together, so each job comes down to isolating one circuit at a time — the rest of the system keeps running while you work.
Underslab & embedded piping
Leak-check refrigerant lines before they're covered by concrete or ceiling grid, when a re-braze costs minutes instead of a demo and repour.
Rack & case tie-ins at startup
Every field-run braze and header connection verified before the system takes its first refrigerant charge.
Multi-store build programs
A standard tightness-test method and documentation set that travels from one store opening to the next.
Rack & case surveys
Scheduled leak checks across compressor racks and display cases to catch drift before it crosses a reportable threshold.
Walk-in coolers & freezers
Door gaskets, evaporator coils, and line sets checked on a recurring cycle, not just when something's already low.
Portfolio maintenance contracts
One leak-detection method and one documentation format across every store in the contract, however many sites that covers.
Give your customers documentation they can actually file
EPA's updated refrigerant management rules (40 CFR Part 84, Subpart C, effective January 1, 2026) tightened both the threshold for coverage and the paperwork that follows a leak. A clean tightness test at startup gives a new system a leak-free baseline; an annual survey on an existing one keeps it from drifting past the threshold in the first place.
What the rule requires
- Systems with 15 lbs or more of HFC or HFC-blend refrigerant (GWP over 53) are covered — comfort cooling, commercial refrigeration, and industrial process refrigeration each have their own trigger rate.
- A leak rate must be calculated every time refrigerant is added above the threshold.
- Commercial refrigeration equipment over the 20% annual leak rate has 30 days to complete repair and pass a follow-up verification test.
- Systems reaching 125% of full charge lost in a calendar year must be reported to the EPA as a chronic leaker by March 1 of the following year.
What a DXH-240 survey gives you to hand over
- A leak-rate calculation worksheet you can fill in from the survey.
- Before-and-after ppm readings at every confirmed leak location.
- Joint-level notes tagged to the customer's equipment IDs.
- A verification-test record once repairs are complete and ready to file.
Built for the contractors who bid this work
Mechanical contractors on new builds
Piping subs on big-box and grocery construction who want every braze verified and documented before the ceiling closes or the slab pours.
Refrigeration service contractors
Companies bidding on or holding annual leak-check and preventive-maintenance contracts across a store's refrigeration systems.
Multi-site & regional providers
Contractors managing recurring annual survey work across a whole retail portfolio, who need one method and one documentation format for every store.
Common questions from contractors
Do I need to recover refrigerant before testing?
Depends on the job. On an existing system, yes — recover the charge with certified equipment, reclaim it, and evacuate before tracer gas goes in. On new construction, there's nothing to recover: the piping has never been charged, so you evacuate and go straight to tracer gas.
Should new piping be tested before the refrigerant charge?
Yes. Tracer gas testing before charge is roughly 1,000 times more sensitive than a standard pressure-decay test, and it catches leaks while the joint is still open — before insulation, a ceiling, or a slab goes over it.
How is an annual check different from investigating a known leak?
An annual or preventive-maintenance check runs on a schedule, whether or not there's a known problem — the goal is catching a developing leak before it crosses the 20% EPA threshold, not just responding after refrigerant is already low.
Is the 5% H2 / 95% N2 tracer gas safe to use in an occupied store?
Yes. At 5% hydrogen in 95% nitrogen, the mixture is non-flammable — hydrogen needs roughly 5.7% concentration in nitrogen before it can sustain combustion, so the working mixture stays well under that line. It's also non-toxic and leaves no residue once vented.
Will the DXH-240 work on CO₂ transcritical or secondary loop systems?
Yes. The same evacuate-and-charge sequence applies to CO₂ (R-744) transcritical racks, secondary glycol loops, and standard HFC/HFO systems alike.
What's the smallest leak the DXH-240 can find?
Down to about 1×10⁻⁵ cc/s with the H2/N2 tracer mixture — roughly the equivalent of a 1 gram/year refrigerant leak — with three sensitivity settings to help you dial in on a specific joint.
Do I need a special certification to use it?
The detector itself doesn't require certification to operate. You'll still need an EPA Section 608 certification to legally recover, evacuate, and recharge a refrigerant circuit on an existing system — the same as any other refrigerant service work.
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