How to Pick a Size by Extinguisher Capacity

Extinguisher cabinets are sized differently from fire hose cabinets. A fire hose cabinet is sized by NFPA 14 standpipe class — Class I needs a certain cabinet, Class III needs another. An extinguisher cabinet, by contrast, is sized by the physical cylinder it houses. Start with the extinguisher weight in pounds (or kilograms), then pick the XMDDG model that fits that cylinder.

The three size tiers are:

Full XMDDG Dimensions Table

Complete dimensions in millimetres and inches for all four XMDDG sizes. These are the base painted indoor dimensions — variants (outdoor / stainless / recessed) use the same external body dimensions with minor adjustments noted further down.

Weights are approximate for a 1.0–1.2 mm cold-rolled carbon steel body without the extinguisher installed. Stainless steel variants (XMDDG-SS) are approximately 5–8% heavier; outdoor weatherproof variants (XMDDG-OD) are approximately 10–15% heavier because they use thicker 1.2–1.5 mm sheet steel to withstand outdoor impact and handling.

Rough Opening for Recessed Installations

For recessed flush-mount extinguisher cabinets, the rough opening in the wall framing is 20 mm wider and 20 mm taller than the cabinet body, giving installers shim room during seating. The factory-fitted trim ring covers any minor framing tolerance. All four XMDDG sizes are offered in the recessed configuration (unlike the hose cabinet range, where the smallest size is not offered recessed).

Notice the minimum wall depth increases with cabinet size — the XMDDG12 needs only 170 mm of wall cavity while the XMDDG42 needs 240 mm. This matters for drywall construction: a standard 100 mm metal stud wall (about 100 mm internal cavity) will not accept any XMDDG recessed cabinet. 150 mm stud walls accept the XMDDG12 with marginal clearance. 200 mm stud walls accept everything up to XMDDG42 comfortably. If you are unsure about your wall depth, see the compatibility table in Section 6.

Size Differences Between Variants

Unlike the SG24 fire hose cabinet range where all three variants (glass / stainless / recessed) share the same external body, the XMDDG extinguisher cabinet variants have small but real dimensional differences because they are engineered for different environments. The table below summarises which XMDDG sizes are available in each variant and any dimensional notes.

Why XMDDG12 is only offered as recessed

The 5 lb XMDDG12 is only made in the painted indoor and recessed configurations. It is not offered as an outdoor weatherproof variant because 5 lb extinguishers are almost never installed outdoors — outdoor code applications (gas stations, parking decks, construction sites) typically require a minimum 10 lb unit. It is also not offered as stainless steel because the facility types that demand stainless (food, pharma, marine, chemical) typically use 10 lb or 20 lb extinguishers for faster incipient-fire suppression in larger hazard areas.

Small dimensional differences between variants

The three variants share nominal external dimensions at any given size, but small differences exist:

• Outdoor (OD) variants use 1.2–1.5 mm sheet steel (thicker than indoor 1.0–1.2 mm) which adds about 1 mm to the effective wall thickness on each side. Nominal dimensions are unchanged for specification purposes but the cabinet weight is 10–15% higher.
• Stainless (SS) variants use 1.0–1.2 mm 304 or 316 stainless sheet, so dimensions match indoor painted exactly. The cabinet is about 5% heavier because stainless is slightly denser than carbon steel.
• Recessed (R) variants omit the back plate (replaced by the wall itself) and add a factory trim ring. Total projection from the finished wall is only 20–25 mm (the trim ring) instead of the full body depth.

Internal Clearances — What Actually Fits Inside

External dimensions set the wall footprint; internal dimensions determine whether your extinguisher actually fits. The table below gives approximate internal clearances after accounting for the door frame, hinges, mounting brackets and interior signage. Use these numbers when confirming that a specific extinguisher brand and model will fit without binding on the door or hinge.

Portable extinguisher cylinder diameters and heights vary slightly by manufacturer — a 10 lb ABC extinguisher from one brand might be Ø 150 × H 530 mm while another is Ø 160 × H 550 mm. The XMDDG22 is sized with enough margin to accept any standard 10 lb commercial extinguisher with at least 20–30 mm of clearance on all sides, but always verify with the specific cylinder datasheet before finalising your order. For unusual extinguisher geometries (long-hose accessories, side-mounted pressure gauges, or wheeled units) the XMDDG42 with its additional depth is the safer specification.

Wall Depth Requirements (Recessed Installations)

Because the XMDDG range spans four different cabinet depths (150 to 220 mm), wall compatibility depends on which size you are installing. The smallest XMDDG12 needs only 170 mm of wall cavity; the largest XMDDG42 needs 240 mm. The table below shows which wall types can accept which XMDDG sizes in the fully recessed configuration.

The practical takeaway: 200 mm metal stud walls accept any XMDDG size up to and including the XMDDG42 (marginal), and 300 mm CMU block accepts everything comfortably. For thinner walls, pick a smaller XMDDG size or switch to surface-mount. If your project mixes different cabinet sizes across different wall types, you may need to specify different XMDDG models in different locations — for example, XMDDG22 recessed in drywall corridors and XMDDG32 surface-mount in shallow partition walls.

Metric / Imperial Conversion Reference

For projects specified in imperial units, the XMDDG dimensions convert to approximate round-ish imperial values. Use the table below when translating between the metric datasheet and an imperial drawing.

On a U.S. imperial drawing, it is common to round these values for readability — calling out an XMDDG22 as “27 inches × 9-1/2 × 7” on the drawing notes is fine. The manufactured dimension is still metric, so the spec text should reference the actual millimetre value as the authoritative number.

Extinguisher Brand Compatibility Notes

The XMDDG internal clearances are sized to accommodate any standard commercial portable extinguisher at the rated weight. Below are representative cylinder dimensions from the major global manufacturers — these numbers come from published datasheets and are for reference only; always confirm with the cylinder supplier before ordering.

The 10 lb CO₂ row is worth highlighting: CO₂ cylinders are taller than equivalent-weight ABC powder cylinders because CO₂ is stored at higher pressure in a thicker-walled cylinder. A 10 lb CO₂ in an XMDDG22 fits, but with less vertical clearance than a 10 lb ABC — check the discharge horn position to confirm it clears the cabinet interior. For CO₂-heavy environments (commercial kitchens, electrical rooms, server rooms) the XMDDG32 with its 800 mm height is the more comfortable specification.

Custom Sizes and Special Orders

The four XMDDG standard sizes cover almost every commercial portable extinguisher installation. For projects outside the standard range, custom sizes are available to order. Typical reasons to go custom include:

• Non-standard extinguisher geometry — very long hose accessories, side-mounted gauge panels, retrofitted monitoring sensors, or wheeled units that do not fit the standard wall-mount envelope.
• Dual-extinguisher cabinets where a single cabinet must hold two extinguishers (one ABC and one CO₂, for example) at the same location — usually a wider custom width with a central divider.
• Integrated signage or indicators such as illuminated LED signage, tamper sensors or alarm contacts that require additional internal space or external housing.
• Heritage retrofits where an existing wall recess from a previous installation has a non-standard opening size and the new cabinet must fit the existing opening.
• Architectural requests where the designer wants the cabinet proportioned to match wall panelling modules or visual alignment with adjacent elements.

Custom cabinets typically add 4–6 weeks to standard lead time. Minimum order quantities apply for non-standard dimensions — usually 10 units. Email sales with a drawing, target dimensions and the extinguisher specification, and we confirm feasibility and lead time within one business day.

Frequently Asked Questions