In a business can we purchase goods above rs.20000 in cash

Hi All,

         I started a business of Petrol Pump 4 years back. I purchase petrol and diesel from other pumps locally ( as my quota is small ). All the purchases are done in cash. But in last two years our purchases per bill exceeded Rs. 20000. Normally our daily sales amounts to Rs.50000. Means we purchase Petrol in 2 parts i.e. of Rs 25000 bill each ( approx.). 

My yearly turnover is of around 1.25 CR totally in cash and my firm is in TAX AUDIT.

My question is weather in this situation payment in cash above Rs.20000 is permissible. Or the IT department will disallow it.

Thanks