Functional Requirements for Dry Powder Tender for Fire Brigade Use
1980 Edition

IS 955 defines the functional and design requirements for dry powder tenders intended for firefighting, focusing on a vehicle with 150 kg dry powder capacity. It specifies closed seating for two personnel plus driver with independent seats, cabin doors hinged at the front and opening outward with dual catch mechanisms, and provisions for housing the powder vessel and firefighting equipment at the rear. The floor in the rear section utilizes chequered steel plates, while the canopy roof is covered with aluminum sheets. Appendix A lists the mandatory equipment including ladders and various types of axes and shovels. The vehicle gearbox must have at least three forward gears and one reverse gear, with an accessible oil level indicator. Accessories include a 250 mm diameter fire bell of natural tone, fog lamps, reversing lights, trafficators with indicator lights, windshield wipers, search and spotlights, and inspection lamps mounted on the control panel.

The standard mandates seating for two men plus driver in a closed cabin with separate seats, front-hinged outward opening doors equipped with double catch striking plates and locks designed to prevent accidental opening from inside. The rear body is designated for the dry powder vessel and firefighting tools, with chequered plate flooring and aluminum sheet roofing. All materials and construction workmanship must ensure durability and safety, with accessories and fittings conforming to relevant compressed gas cylinder standards. Numerical specifications are rounded off as per updated guidelines.

Materials selected for the tender must balance lightness, strength, and durability, especially since the vehicle carries 150 kg of dry powder. Components contacting water or fluid pathways should be made from corrosion-resistant substances such as stainless steel or brass. Parts exposed to atmospheric conditions must either be inherently corrosion-resistant or treated with protective coatings such as galvanization or painting. For design and construction, reference IS 7372-1974 is applicable instead of IS 7342-1974.

The vehicle design must comply with criteria ensuring all water-contact parts are corrosion-resistant and atmospheric metal parts are suitably protected. The construction quality includes attention to workmanship, finish, and accessories, alongside mandatory acceptance tests. Equipment such as extension ladders, various axes, and shovels are specified with corresponding IS codes. Numerical data must be rounded appropriately, and corrosion protection is emphasized for longevity and safety.

The chassis must support the full specified load and meet precise dimensional requirements outlined in IS 955. It shall be a four-wheel vehicle with four-wheel drive, featuring a stabilizer on the rear axle and robust drag hooks front and rear. Lubrication points must be easily accessible and clearly marked if remote. Suspension employs high-grade elliptical leaf springs conforming to IS 1135-1973, with semi-floating rear axle and shock absorbers on all wheels. Preferred driving position is forward or semi-forward. The gearbox requires at least three forward gears plus one reverse, with oil level preferably checked by dip-stick.

The engine must deliver a continuous power output of no less than 30 kW and an auto-rated power of at least 52 kW, featuring four or more cylinders. Petrol engines must incorporate dual coil ignition with suppression of high tension loads. Starting systems should include reliable electric starters and ideally a hand-start option. The vehicle is expected to reach 95 km/h on level ground without a transfer case and accelerate from standstill to 60 km/h in under 40 seconds when fully loaded. It must also be capable of starting on a 1 in 4 gradient without warm-up even in low temperatures. Cooling water temperature should be thermostatically regulated.

The fuel tank capacity shall be at least 50 liters, equipped with a gauge visible on the driver’s instrument panel. The filling orifice must have a minimum diameter of 50 mm, be easily accessible, and clearly labeled as 'Fuel'. For petrol engines, the cap must include an anti-flash device to prevent ignition hazards. Exactly one mechanically driven fuel pump is required.

The tender's electrical system is standardized at 12 volts, using a lead-acid battery conforming to IS 7342-1974. The dynamo or alternator must be heavy-duty for reliable operation. Essential accessories include a 250 mm diameter fire bell producing a natural tone per IS 928-1964, fog lamps positioned for reversing assistance, low-mounted reversing lights, trafficators with instrument panel indicators, one pair of windshield wipers, maintenance tools beyond the chassis kit, a searchlight with adjustable beam and a 30 m cable limiting voltage drop to 2 volts, a spot light near the driver’s side, and inspection lamps with control panel sockets.

The tender must carry two dry powder cylinders, each with 75 kg capacity, connected individually to nitrogen cylinders with no less than 1.7 cubic meters capacity. Nitrogen cylinders are fitted with reducer valves and pressure regulators. A 10-meter long pneumatic rubber hose, 25 mm in diameter, is used for powder discharge, operated one cylinder at a time. Minimum powder discharge rate is 2.5 kg per second with a throw distance of at least 10 meters and a minimum discharge duration of 25 seconds. A minimum of 85% of the powder content must be discharged. Cylinders shall have filling orifice diameters of at least 15 cm and drain orifices of 50 cm at the base, with safety and blow-off valves. Working pressure is capped at 15 kgf/cm² at 16°C, with hydraulic test pressure at 30 kgf/cm². The dry powder conforms to IS 4308-1967.

The vehicle cabin is enclosed, designed to seat two men plus the driver, with all seats independent. It has two doors, one on each side, front-hinged opening outward, secured with double catch striking plates to prevent accidental opening from inside. The rear body houses the dry powder vessel and firefighting equipment as per Appendix A. Flooring in this area uses chequered plates, and the roof is covered with aluminum sheets. The chassis must support the full load and maintain a minimum road clearance of 20 cm when fully loaded. The bodywork width must not increase beyond 20 mm over chassis width, and overall height including mounted ladder must not exceed 3 meters. Accessories include fire bells, fog lamps, reversing lights, trafficators, windshield wipers, maintenance tools, search and spot lights, and inspection lamps.

The ladder gallows is constructed to support a 4.5-meter extension ladder per IS 4571-1977, enabling swift and unobstructed withdrawal from the rear. The head lock mechanism must be positively locking to secure the ladder. Equipment layout ensures no interference with ladder removal. The vehicle’s maximum height with the ladder mounted is 3 meters, maintaining a minimum road clearance of 20 cm fully loaded and maximum width of 2 meters.

A recessed tray is provided on the appliance for the standard tool kit specified in Appendix A. The container securely holds tools including the 4.5 m ladder, various axes, and shovel, ensuring easy access and protection during transit. Materials and finish conform to IS 955 workmanship standards, and the design facilitates quick removal and replacement in emergencies.

The fire tender must achieve a maximum speed of 95 km/h on level terrain without engaging the transfer case. Acceleration from rest to 60 km/h when fully loaded must occur within 40 seconds. The vehicle must be capable of starting on a 1 in 4 gradient (25%) under full load. The gearbox requires a minimum of three forward speeds and one reverse, with provisions for oil level inspection preferably via dip-stick.

Braking must be present on all four wheels, using hydraulic systems preferably assisted by vacuum or air. The brakes should stop the fully loaded vehicle traveling at 30 km/h within 6 meters on a dry surface. The handbrake must hold the vehicle stationary on a 1 in 4 gradient in neutral gear, ensuring safety on slopes.

The tender must remain stable and resist overturning when tilted to 25° from horizontal under full load conditions excluding crew weight. Stability is expressed through the overturning angle θ, with the relationship tan θ = (B/2h), where B is the track width and h is the center of gravity height. To meet the standard, B/(2h) must be at least 0.466, ensuring safe operation on slopes and uneven terrain.

All components must exhibit excellent workmanship with smooth surfaces free of defects such as cracks, burrs, or sharp edges. Water-contact parts are made from corrosion-resistant materials like stainless steel or brass, while exposed metal parts are either corrosion-resistant or have protective surface treatments like galvanizing or painting. The tender must uphold stability requirements, resisting tilts up to 25° when fully equipped and loaded.

The instruction book must provide detailed operating and routine maintenance procedures, along with an illustrated and itemized list of spare parts referencing all wear components. The appliance should be painted fire-red (Shade No. 536 as per IS 5-1979), using paint conforming to IS 2932-1974. Appendix A lists mandatory equipment including extension ladders, axes, and shovels. Accessories specified include fire bells, fog lamps, reversing lights, trafficators, windshield wipers, tools, search and spot lights, and inspection lamps.

The manual must cover detailed operating instructions and routine maintenance guidelines. It should include an itemized and illustrated spare parts catalog with reference numbers for all wear parts to aid in upkeep and repairs. Painting requirements specify fire-red color matching IS 5-1979 Shade No. 536 and adherence to IS 2932-1974 paint quality standards.

Mandatory accessories include a 250 mm fire bell producing a natural tone per IS 928-1964, mounted externally and operable from the driver's position; fog lamps arranged to assist reversing; low-mounted reversing lights; trafficators with indicator lights on the instrument panel; a pair of windshield wipers; maintenance tools beyond the standard chassis kit; an adjustable searchlight with a 30 m TRS cable limiting voltage drop to 2 volts; an adjustable spot light near the driver’s enclosure; and a protected inspection lamp with plug and socket on the control panel.

Per Appendix A, the tender must carry one 4.5 m extension ladder (IS 4571-1977), two fireman's axes (IS 926-1970), one large axe and one hand axe (both IS 5505-1969), and one shovel (IS 274 Parts I & II). The vehicle must be painted fire-red (Shade No. 536, IS 5-1979) with paint conforming to IS 2932-1974 to ensure visibility and durability.

All equipment must be clearly marked according to their respective IS codes. The tender carries the standard firefighting equipment listed in Appendix A, including ladders, axes, and shovels. Accessories such as fire bells, fog lamps, reversing lights, trafficators, windshield wipers, tools, search and spot lights, and inspection lamps must be properly identified and functional. Voltage drop in accessory cables should not exceed 2 volts, calculated as V_drop = I × R, where I is current and R is cable resistance.