Anti-Smog Gun Selection Guide — Throw, Tank Size and What Officers Actually Look For

During GRAP-3 and GRAP-4 the anti-smog gun becomes the single most visible piece of compliance equipment on a Delhi NCR site. Officers photograph it, PTZ cameras capture it running, and neighbours complain to DPCC if it is not. Getting the specification wrong wastes both capex and water.

Match throw distance to plot geometry, not brochure claims

The most common mistake is buying a 100m-throw gun for a 30m-wide plot. On smaller sites a 30–50m throw gun mounted at boundary corners provides better coverage than one oversized unit that overshoots the site.

• Under 1,500 sqm — one 30–50m throw gun on a mobile trolley
• 1,500–3,000 sqm — one 50–80m throw gun, ideally roof-mounted
• Above 3,000 sqm — 100m gun plus perimeter sprinklers along the barricade

Tank size decides how often you refill

A gun with a 5,000L tank running full throttle empties in under 90 minutes. During GRAP-4 the officer expects near-continuous operation from 8am to 6pm — plan the water source before you buy the gun.

• Municipal tanker refills — cheapest but unreliable during peak hours
• Borewell + storage tank — best for long projects, needs one-time CGWA permission
• STP treated water — free and CPCB-preferred if a plant is within 5km

What officers look for during a spot check

• Gun physically present and connected, not stored under tarpaulin
• Water tank at least half-full at the time of inspection
• Operator on site trained to switch it on within 30 seconds
• Daily log book of hours run, signed by the site engineer
• PTZ camera view covering the gun so DPCC can verify from remote

GRAP-stage operating rules

The Commission for Air Quality Management links smog-gun operation to the active GRAP stage. Know the current stage and adjust — running below the mandated hours is treated as non-operation.

1. GRAP-1 (AQI 201–300): 4 hours daily during working shifts
2. GRAP-2 (AQI 301–400): 6 hours, including peak-dust activities
3. GRAP-3 (AQI 401–450): continuous operation during all excavation and material handling
4. GRAP-4 (AQI 450+): non-essential work stops; sprinklers run continuously

2026 price band — genuine equipment only

A 30–50m mobile smog gun with 3,000L tank lands at ₹3.5–5 lakh; a 100m diesel-hydraulic unit with 5,000L tank lands at ₹9–14 lakh. Below these bands the units are either underspec, refurbished or use plastic-body pumps that fail within a season.

Rent versus buy

For projects under 12 months, monthly rental (₹35k–90k depending on capacity) is usually cheaper than owning. For 18-month-plus projects, ownership plus quarterly AMC works out lower per month — and gives DPCC a stronger compliance signal.