Scales for Ex Areas

Buying guide

Which zone and gas group the scale must match?

The purchase starts with the hazardous area classification, because a scale certified for the wrong zone cannot lawfully enter the room, whatever its weighing performance. An explosive atmosphere is graded by how often it is present: gas zones run 0, 1 and 2, dust zones 20, 21 and 22, with the lower number meaning the danger is there for longer. A unit marked for zone 1 covers zone 2 as well, but never the reverse. On top of the zone comes the gas group, IIA through IIC, and the temperature class, T1 to T6, which caps the surface temperature the device may reach. A buyer confirms the exact marking on the nameplate against the plant's own area drawing before anything else, because the certificate, not the datasheet, decides where the instrument may stand.

Protection method matters alongside the marking. Intrinsically safe designs limit the stored energy so that no spark can ignite the atmosphere, and they suit the most demanding gas zones; flameproof enclosures contain any ignition inside a rated housing instead. The method affects how the scale is wired, whether a safety barrier sits between it and the control room, and what a technician may do to it in the field.

On a used unit the certificate is the first thing to verify. An Ex certification is tied to the device as built, so any repair, modified cable gland or replaced display can void it unless carried out to the original specification. Check that the certificate number is legible, that the documentation accompanies the scale, and that nothing on the enclosure has been opened or substituted. Calibration is a separate question: weighing accuracy drifts with handling and age, and a balance that reads correctly still needs recalibration against known masses before it enters service.

Price is where the range widens most. A small intrinsically safe bench balance sits near the lower figure, while a large floor platform for a production hall reaches the upper one, and the average of EUR 5.944 falls between the two. The dominant makers here are Radwag, RADWAG, Ohaus, Mettler Toledo, Minebea Intec, and their presence shapes what a buyer can expect: parts and comparable models are easier to find, and a used listing from one of them is simpler to value against a new one. For a buyer working to a budget, the used and refurbished units listed for sale cost less than new equivalents, though at 1 percent of stock they are the exception rather than the rule. What a certified scale costs is driven far more by its platform size and zone rating than by its brand.

Types of Scales for Ex Areas

Which weighing types are listed here?

Among the listings that specify a type, the catalogue sorts into hazardous area equipment, intrinsically safe equipment, platform scale, industrial scale, weighing instrument, process control equipment. The two that define the category are hazardous area equipment and intrinsically safe equipment: these are not separate kinds of scale so much as the certification class every unit here belongs to, describing how the device is rated for an explosive atmosphere rather than how it weighs. A platform scale is the large-footprint form, a low deck a pallet or drum can sit on, used where whole containers are weighed on a factory floor. An industrial scale is the broader bench and floor family built for production rather than the laboratory, rugged and often rated for coarser resolution. A weighing instrument covers the finer bench balances, where readability to a milligram or better is the point. Process control equipment sits at the edge of the group, where the scale feeds a dosing or batching line and its reading drives a valve or a feeder rather than a printout.

These weighing instruments do real work in biotechnology and pharmaceutical manufacturing, where solvent handling means the gravimetric analysis itself often happens inside a classified area. A certified balance performs the formulation and sample preparation steps for bioprocessing and biomanufacturing where flammable solvents are present, so an explosion proof balance for solvent weighing is a routine fixture in a pharmaceutical filling suite. In molecular biology and microbiology labs that store and dispense flammable reagents, an intrinsically safe laboratory scale for hazardous areas lets protein purification and media preparation proceed without moving the weighing step out of the controlled room.

The brands behind the Ex-area scale listings

The makers that recur across these listings are Radwag, RADWAG, Ohaus, Mettler Toledo, Minebea Intec. Their weight in the catalogue is practical rather than promotional: where several listings come from the same maker, a buyer can compare resolution, platform size and zone rating across models that share a design language, and parts for a common model are easier to source. A used unit from one of these names is also simpler to value, because a new equivalent usually exists to price it against. The brand does not override the certificate, though; a Radwag bench balance and a Mettler Toledo platform are chosen on their zone marking and capacity first, and on the badge second.

What condition and price look like here?

Of the current stock, 1 percent of the listings are used. Prices run from EUR 281 to EUR 27.728, with an average of EUR 5.944. That spread covers the full distance from a compact intrinsically safe bench balance to a large certified floor platform, which is why the top figure sits so far above the mean. Both British and American spellings of the surrounding terms, catalogue and catalog alike, point to the same set of listings.