Product Overview
Intrinsically Safe Personal Noise Dosimeter for Class I Hazardous Locations
Condition
Used, pulled from service, and it looks the part. The textured black case shows worn corners and edges where the finish has gone through to bare plastic, light scuffs across the face, and shop grime settled in the seams. The yellow-green MK-3 AUDIO DOSIMETER graphic, the AMETEK logo and US PAT. 4,554,639 below them are all intact and legible. In two of the photos the LCD is live: one frame reads 58.6, another reads 71.7 with BATT OK and the Lavg/Leq annunciator showing, so the unit powered up and drove its display when it was photographed. The bright metal belt clip is scratched but straight. The remote microphone is present with its foam windscreen, coiled cable, a white zip tie and a spring clip that carries old tape residue. The battery bay is shown open: the 9V snap connector with red and black leads is intact and the gold edge-connector pins are clean, and inside sit an Ametek Mansfield and Green Division Q.C. inspection sticker dated DEC 7 '98 and a green Ametek Largo, Florida label reading SERIAL NO: 035281. No calibration, accuracy, memory or run-time testing has been done here. Five units are in stock and the photos show one representative unit, so the serial number and the exact pattern of wear will vary.
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Product Overview
The Ametek MK-3 is a body-worn audio dosimeter from the Mark series, built to log a worker's personal noise exposure in places an ordinary sound level meter is not certified to enter. The nameplate on the back reads INTRINSICALLY SAFE / SECURITE INTRINSEQUE, Class I Group C, D, EXIA, temp code T3C, carries a CSA mark, and covers models MK-1, MK-2 and MK-3 under U.S. Pat. No. 4554639. The label wrapped around the base adds UL Listed 973X for Class I Group C, D, Class II Group E, F, G and Class III temp code T4, an FM Approved mark, MODEL MARK SERIES, MADE IN USA, and the instruction INDOOR ONLY. A separate plate carries MSHA approval 2G-3390-0, tested in methane-air mixtures for electrical safety only. Per the original listing the instrument measures roughly 70 dB to 140 dB, reads A-weighted by default with optional C-weighting, resolves Leq to 0.1 dB with selectable logging intervals, stores over 30 hours of data, and meets OSHA, MSHA and EN 61252. A function legend printed on the case side is only partly visible in the photos; the readable lines include Lmax, an average reading, PROJECTED 8 HR. DOSE and FROM START TO >115 dB. Two metal toggle switches sit in a recessed panel on the base, the left one marked I and O, with a remote lapel microphone on a coiled cable feeding the top.
Key Features
- Model: Ametek MK-3 personal audio dosimeter, Mark series, MADE IN USA per the base label
- Intrinsic safety plate: Class I Group C, D, EXIA, temp code T3C, CSA marked
- Base label: UL Listed 973X, Class I Group C, D; Class II Group E, F, G; Class III temp code T4
- FM Approved, marked INDOOR ONLY on the same label
- MSHA approval 2G-3390-0, tested in methane-air mixtures for electrical safety only
- Battery per the labels: 9V alkaline only, NEDA 1604A or equivalent, with Energizer #522 named on the CSA plate and abbreviated ENGZR #522 on the FM line
- Measurement range approximately 70 dB to 140 dB, per the original listing
- A-weighting standard with optional C-weighting, per the original listing
- Leq resolution 0.1 dB with selectable logging intervals, per the original listing
- Data storage of 30-plus hours, per the original listing
- Stated compliance with OSHA, MSHA and EN 61252, per the original listing
- U.S. Pat. No. 4554639; the safety plate covers MK-1, MK-2 and MK-3
- Includes the remote microphone with foam windscreen, coiled cable and spring clip as photographed
- Bright plated metal belt clip on the rear for body wear; clip material is not marked
Applications
- Refinery safety manager running an OSHA noise survey on a unit where only intrinsically safe instruments are permitted
- Mine safety technician who needs an MSHA-marked body-worn dosimeter for underground shift exposure work
- Industrial hygienist collecting Lavg, Leq and projected 8-hour dose on a plant floor
- Instrument technician rebuilding or cannibalizing 1980s and 1990s Ametek Mark series dosimeters for parts
- Safety trainer who wants a real hazardous-location dosimeter as a classroom prop rather than a photo on a slide
Frequently Asked Questions
Does it power up?
The unit in the photos did. Two frames show the LCD lit with BATT OK and live readings of 58.6 and 71.7, and the Lavg/Leq annunciator active. That is the extent of what we checked. Accuracy, calibration, logging over a full shift and memory retention were not tested.
What battery does it take?
Go by the labels on the instrument, not by a substitute. The base label reads ONLY WITH 9V ALKALINE BATT. NEDA 1604A OR EQUIV., and the FM line beside it reads FOR USE WITH 9V ENGZR #522 BATT. ONLY. The CSA plate on the back spells it out: FOR USE WITH 9V ENERGIZER #522 BATTERY. Both plates warn that substituting components may impair intrinsic safety, so the battery choice is part of the approval, not a preference.
What is included?
The dosimeter itself with its metal belt clip, and the remote microphone with foam windscreen, coiled cable, zip tie and spring clip, exactly as photographed. No battery is visible in the open battery bay in the photos. No calibrator, charger, manual, software or carrying case is included.
Can I use it for compliance records straight out of the box?
Not on our word. Nothing here has been calibrated or certified. Treat it as an uncalibrated instrument: check it against an acoustical calibrator and against your own hearing conservation program before any exposure record depends on the numbers it produces.
What am I actually taking on with a used dosimeter like this one?
Straight answer: an intrinsically safe instrument pulled from service, sold as it sits. What we can show you is in the photos - a worn but complete case, legible UL, FM, CSA and MSHA markings, the microphone and belt clip still with it, a clean battery bay and connector, and an LCD that lit up and read out when the pictures were taken. What we cannot show you is calibrated accuracy, battery run time, logging behavior across a shift, or memory integrity, because none of that was tested. The photos are the spec. If you need a dosimeter that arrives certified and survey-ready, this is not that unit. If you want a Mark series body of the kind photographed here for a rebuild, for spares, for training, or to put back into service behind your own calibration, that is what this is. This one clears our free-shipping line on its own, and orders leave the Idaho warehouse the same or next business day.
Somebody in Largo, Florida signed this one off in December of 1998 and sent it out to a place where a spark mattered more than a scratch. The scratches came anyway, and they are yours now, along with whatever it gets asked to measure next.
