puc machines as the name suggests comprises of two machines as follows
1) exhaust gas analyzer , 4 gas analyzer or petrol puc machines.
2 ) diesel smoke meter .

the above machines are used on pollution testing center to test following parameters

1) co: carbon monoxide
2) carbondioxide
3) hydrocarbon
4) oxygen

this gases are tested in petrol , cng and lpg driven vehicles.

and in case of diesel smoke meter , smoke density is tested.

any one who wants to start the puc business have first buy these machines and after getting relevant permissions from the transport department one can operate and puc center ( pollution under control center).