MEP Design for an Auto-Component Plant: Paint Shop, Compressed Air and Power Distribution

MEP design for an auto-component plant is built around three utilities that carry process risk: the paint shop, with its solvent vapour and fire separation; a compressed air system serving presses, robots and tools; and a power distribution that survives press-line starting and drive harmonics while leaving room to grow. Machine lines are added bay by bay, so design the margins in from the start.

What does a paint shop need from the MEP design?

Paint and solvents bring flammable vapour, so the design tasks are to keep vapour out of ignition range, keep ignition sources out of vapour, and keep a fire contained. Section 37 of the Factories Act sets the legal duty: where a process produces dust, gas, fume or vapour likely to explode on ignition, all practicable measures must be taken to prevent an explosion by effectively enclosing the plant, removing or preventing accumulation of the vapour, and excluding or enclosing all possible sources of ignition. Part 4 of the National Building Code 2016 (clause 6.7.1.1) adds that hazardous activities such as paint stores and spray booths are to be separated from non-hazardous areas, such as offices and canteens, by walls and doors rated for 120 minutes.

Ventilation also sets finish quality, because temperature, humidity and cleanliness of supply air affect the coating. The booth supply plant therefore carries filtration and conditioning as well as the safety function. See battery charging room and paint booth ventilation and industrial exhaust systems.

How much solvent can be stored before a licence is needed?

PESO's guidance on the Petroleum Rules, 2002 classes petroleum by flash point: Class A below 23 degrees, Class B from 23 up to below 65, and Class C from 65 up to below 93. It notes that acetone, ethyl alcohol, methyl alcohol and wood naphtha are also classified as petroleum. No licence is needed to hold Class A petroleum not intended for sale if the total does not exceed 30 litres, kept in stoppered glass or stoneware receptacles of up to 1 litre or metal receptacles of up to 25 litres. The guidance also lists no licence for non-bulk Class B up to 2,500 litres in receptacles not exceeding 1,000 litres. Thinners and washes vary, so read each safety data sheet for its flash point, and confirm with PESO before fixing the store size. The store is a design input: it decides the room size, ventilation and distance from other buildings. See PESO licensing for fuel storage.

A paint shop also touches the approvals. The fire design feeds the Fire NOC, the supply and standby arrangements may need the Electrical Inspector, and the stack and effluent arrangements feed the pollution control board consent. Whether a coating line needs its own consent, and under which category, is a question for the state board, so raise it while the layout can still change. See consent to establish and operate and Fire NOC assistance.

How should compressed air be designed?

Compressed air serves tools, robots, clamps, blow-off and the paint shop's atomising air, and its design is driven by the machine list. For each consumer, note the consumption, the number that run at once and the shift pattern. Then:

• Plant. Several compressors give efficiency at part load and a standby. Place them for ventilation and heat removal, with space for another.
• Quality. Air for the paint shop and for instrument use needs drying and filtration to the level the process requires. Do not run the same untreated header to everything.
• Network. A ring main with sensible pipe sizes keeps pressure drop low. Leakage is a continuing cost and grows with the network's age; plan zone valves and metering so leaks can be found.
• Expansion. Size the main header, and leave stubs, for the planned bays.

The detail is in compressed air for a factory and leaks and piping design.

What do press lines and drives do to power distribution?

Presses, welding cells and robot lines place unusual demands on an electrical system. These are typical effects, to be checked against the actual machines.

• Cyclic and starting loads. Large press motors start with high current and some presses draw power in sharp cycles. The result is voltage dips that upset PLCs and robots on the same bus.
• Welding. Spot welders are intermittent, often single-phase, loads. Spread them across phases and feed them from a separate board.
• Harmonics. Drives and rectifiers distort the current. Detune the power factor capacitors and check transformer heating. See harmonics and inverters.
• Segregation. Give heavy cyclic loads their own transformer or feeder, apart from controls and the paint shop.
• Standby. List what must keep running when the mains fails: paint-shop exhaust, fire pumps, emergency lighting and critical controls. Size the DG from that list; the calculator gives a start.

Check the starting capacity of the supply against the load, using the factory electrical capacity calculator, and see transformer undersizing as a growth bottleneck.

What expansion margins are worth building in?

Equipment can be bought later; space and routes cannot. Reserve these in the base design:

• A bay and foundation for a second transformer, and spare ways in the HT and LT boards.
• A route for busduct or cable tray, with tray capacity spare.
• Stubs and valved connections on compressed air and chilled water headers.
• Fire water storage and pump room capacity worked out for the final hazard, since a new paint line can raise it.
• Effluent and drainage capacity.
• Roof structure strength and area if a solar plant is planned; see solar for auto-component plants.

Expansions in an older plant often trigger fresh compliance, covered in the old factory expansion trap.

How Secured Engineers helps

Secured Engineers designs MEPF in-house, so paint-shop ventilation, fire protection, compressed air and power distribution come from the same drawings. Fire NOC, CEIG and DISCOM net-metering applications are filed in-house. MEPF and solar can sit under one contract. The company works from offices in Noida (Delhi NCR) and Ludhiana, with 535+ projects across 18+ states and 89.77% repeat clients. For a plant, the usual first step is a technical review of the utility layout, the load list and the expansion plan before machines are ordered. See also our automobile and auto-component industry page.

To have an auto plant design reviewed, start from our MEP design and approvals service, send the layout and machine list on WhatsApp, call +91 70099 85817, or ask for a free proposal. For budget ranges, use the MEPF cost calculator.