AMPTEC Research · Intrinsically Safe Bonding Ohmmeters
620LK
UL-913 certified intrinsically safe bonding milliohmmeter for metal-to-metal bond checks in aerospace and fuel-wetted areas.
620LK is the bonding tester you reach for when a bond resistance has to be verified inside a fueled aircraft or another area where a spark is not acceptable. It measures the bond resistance of components and metal-to-metal joints on two low ranges, 200 mΩ and 2 Ω, with ±0.05% accuracy. Commercial airlines and USAF programs use it as their standard bonding meter. Its UL-913 certification and MIL-STD-810 Method 511F compliance are what allow that use in hazardous, fuel-vapor locations.
Overview
AMPTEC 620LK is an intrinsically safe bonding milliohmmeter built for aerospace, defense and industrial bond verification. Intrinsic safety is certified independently to UL-913 and the meter meets MIL-STD-810 Method 511F, so bond resistance can be measured in fuel-wetted hazardous areas without first clearing the vapor. Two ranges cover the job: 200 mΩ with 0.01 mΩ resolution and 2 Ω with 0.1 mΩ resolution, both accurate to ±0.05% of reading and range at a nominal 100 mA test current. A 4½-digit LCD updates once every 3 seconds. Four AA alkaline cells power the unit, which weighs about 3.2 lbs, light enough to carry up to the airframe. Many commercial airlines have standardized on it, and AMPTEC manufactures under ISO 9001:2015. Before ordering, decide which probe set you need; the 5-pin Trident terminal takes the 630-series Kelvin probes, and a 630-100 padded case protects the meter on the ramp.
Key specifications
| Ranges | 200 mΩ / 2 Ω |
|---|---|
| Resolution | 0.01 mΩ / 0.1 mΩ |
| Accuracy | ±0.05% of reading & range |
| Nominal test current | 100 mA (both ranges) |
| Display | 4½-digit LCD |
| Update rate | 1 reading per 3 seconds |
| Power | 4× AA 1.5 VDC alkaline batteries |
| Max. internal voltage | 6 VDC |
| Open-circuit voltage | ~5 VDC |
| Max. input voltage | 250 VDC |
| Operating temperature | -20°C to 50°C |
| Temperature coefficient | ±0.0025% per 1°C |
| Terminal | 5-pin Male Trident |
| Dimensions | 7.69″ × 7.56″ × 3″ |
| Weight (unit) | 3.2 lbs |
| Certifications | UL-913 · MIL-STD-810 Method 511F · ISO 9001:2015 |
Features
Certified intrinsically safe
Independently certified to UL-913 and compliant with MIL-STD-810 Method 511F, so bond resistance can be measured in fuel-vapor hazardous areas.
Two low-resistance ranges
200 mΩ and 2 Ω ranges with 0.01 mΩ and 0.1 mΩ resolution, enough to confirm a bond joint against a milliohm-level limit.
Accuracy you can audit
±0.05% of reading and range at a nominal 100 mA test current gives repeatable bond readings from one inspection to the next.
Readable digital display
A 4½-digit LCD updates every 3 seconds, so the reading is easy to judge on the hangar floor.
Light and battery powered
Four AA alkaline cells and a 3.2 lb unit weight make it simple to carry to the aircraft or the equipment under test.
Standard on aerospace ramps
Safety certification plus accuracy is why many commercial airlines and USAF programs have adopted 620LK as their bonding tester.
Typical applications
Aircraft maintenance
Airframe bond integrity on commercial aircraft
Maintenance engineers measure electrical bonds on airframe metal parts in the hangar or on the ramp, confirming that skin, structure and ground points stay under the FAA/EASA bond resistance limits so static charge cannot build up and spark. Airlines such as Delta and Alaska Airlines have written 620LK into their routine maintenance procedures.
Defense
Grounding checks on explosive systems to military standards
Around explosives, pyrotechnics or fueled compartments, the meter itself must not become the ignition source. 620LK carries UL-913 intrinsic safety and EU ATEX approval, which lets ground crews and armament technicians measure bridge wire and airframe ground resistance safely. USAF maintenance programs use it widely.
Manufacturing QC
Outgoing bond test on aerospace production lines
At final inspection, aerospace and defense part makers use 620LK to make four-wire measurements on metal-to-metal joints at 100mA nominal current, holding ±0.05% accuracy on the 200mΩ and 2Ω ranges. Every batch is confirmed within its design bond resistance, with records kept for ISO 9001:2015 traceability.
Options and configuration
Tick the options you need. We compile the configuration into a list and carry it into the quote request form.
Standard equipment (included)
Probe and lead options
Carrying accessories
Downloads
Need pricing, specifications or lead time for 620LK?
Also available for rent: 620LK is part of the AMPTEC rental program, for project peaks, calibration backup and pre-purchase trials. Rental inquiry →