Product Overview
Dräger Model 31 Handheld Bellows Pump for Colorimetric Detector Tubes
Condition
Used, clean, and in excellent condition. This is the exact unit in the photos. The grey plastic housing is free of cracks in these views, with the moulded identification panel on the head reading Mod. 31 and the Dräger crest and DRÄGER name moulded into a raised boss on the underside. This is a Dräger pump, plainly marked as one. The black rubber bellows shows all of its convolutions with no splits or tears visible in the photos. The chrome clamp plate and its two slotted screws are in place on the head. The retaining chain is fastened at one end only - the other end is a loose flat metal lug with an empty screw hole, lying free on the bench in the photos. Close-up photos show dark residue and light scuffing around the rim of the tube inlet and a faint hand mark on the grey body behind the inlet, the ordinary traces of field use. Nothing else is included: no detector tubes, no case, no manual, no accessories. We have not flow tested, leak tested, or stroke counted this pump, so treat its function as unverified until you check it yourself.
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Product Overview
The Dräger Model 31 is a manual, handheld gas detector pump built around a rubber bellows rather than a piston or a battery. A short-term colorimetric detector tube is broken open and seated in the head, the bellows is squeezed and released, and roughly 100 cm³ of sample air is drawn through the tube per stroke, where a reagent stain develops for reading against the tube scale. The whole instrument is mechanical, so there is nothing to charge and nothing to boot up, which is why Dräger bellows pumps like this one stayed in service in confined-space and clearance work long after electronic instruments arrived. This particular pump carries the moulded Mod. 31 panel on the head and the Dräger crest and name on the underside, so the maker is not in question, and it is sold as a bare pump body with its clamp plate and retaining chain, exactly as photographed. Stock is one.
Key Features
- Brand: Dräger, with the crest and DRÄGER name moulded into the underside of the body
- Type: manual handheld bellows pump for short-term colorimetric detector tubes
- Stroke volume: approximately 100 cm³ per stroke, nominal for the Model 31
- Operation: one-handed squeeze and release, no batteries or power required
- Tube compatibility: designed around Dräger short-term detector tubes - confirm your specific tube type against Dräger's current documentation
- Markings visible in the photos: moulded Mod. 31 panel on the head, Dräger crest and DRÄGER name moulded on the underside
- Construction: grey plastic housing, black rubber bellows, chrome clamp plate with two slotted screws, retaining chain fastened at one end with its other lug loose
- Included: the pump only, as pictured - no detector tubes, case, or documentation
- Test status: not tested here for flow, leak tightness, or stroke count
Applications
- Safety technician who keeps a mechanical backup pump in the truck alongside an electronic multi-gas meter
- Industrial hygiene instructor demonstrating colorimetric tube sampling to a class without risking a calibrated instrument
- Maintenance shop with a drawer of Dräger short-term tubes and no working pump to draw them
- Instrument collector or restorer after a correctly marked Dräger Model 31 body to service and put back in order
Frequently Asked Questions
Is this a genuine Dräger pump?
Yes. It is a Dräger Model 31, and the body says so itself: the Dräger crest and the DRÄGER name are moulded into a raised boss on the underside, with the factory Mod. 31 panel moulded into the head. No stickers, no relabeling, no guesswork about who built it.
How does a bellows pump like the Model 31 take a sample?
Mechanically. You seat a broken-open detector tube in the head, squeeze the bellows flat, and let it expand, which pulls sample air through the tube. The reagent inside changes color and the length of the stain is read against the printed scale on the tube. The pump moves air; the tube does the measuring.
Are detector tubes included?
No. The five photos show everything in the sale: one Dräger Model 31 pump body with its clamp plate and retaining chain. Tubes are consumable and are bought separately by type and range, so match them to the gas you intend to sample.
Has this pump been leak tested, flow checked, or calibrated?
No. We are generalists in Idaho, not a gas detection service house, and we performed no test of any kind on this unit. Before using it for any measurement, follow Dräger's current instructions for use, including their leak tightness and volume checks, and confirm the pump is fit for your application. Nothing in this listing is a calibration record, a certification, or a statement that this pump is suitable for life safety work.
What are the dark marks around the tube inlet?
The close-up photo shows dark residue and light scuffing on the rim of the inlet and on the rubber nipple, plus a faint mark on the grey body behind it. That is where broken glass tubes are inserted and removed hundreds of times, so it is the first place a working pump shows its history. The bellows, housing, and clamp plate all photograph intact, and the chain itself is unbroken, though its free lug is unfastened.
What am I taking on with a used detector pump instead of a new one?
You are taking on the verification. What you get is defined and photographed: this one specific Dräger Model 31, one in stock, grey housing uncracked in these views, bellows unsplit in the photos, chain lug loose at one end, moulded Dräger markings legible, sold as-is with no test data behind it and no tubes in the box. What you do not get is a leak certificate, a flow number, or any promise about safety-critical performance - the photos are the spec, and the checkout is yours to run. Shipping is $8 flat rate and free once your order passes $28, and orders leave our Idaho warehouse the same or next business day.
Before gas detection meant a display and a firmware revision, it meant a hand squeeze, a glass tube, and a color you read with your own eyes. Prove this one out on the bench, and a purely mechanical instrument goes back to the simplest honest work there is.
