The full performance testing of a fan can be extremely expensive and with small fans can even exceed the cost of the fan itself. Suppliers and purchasers should always consider, in the first instance, whether this expense is justified.At the customer’s request, and by agreement with the supplier, the specified operational parameters shall be verified by the supplier. The method and scope and price of testing shall be agreed between the customer and supplier. The scope of testing shall take into account aspects such as the tests required, the size of the fan, the facilities available and the agreed tolerance grade.