60                                                             400

In this example, the drain intervals and iron levels are not consistent.

The trend here will not be meaningful unless the wear rates are calculated.

The wear rate will be the PPM of wear per 100 hours of operation, i.e.:

75 ÷ 5.00 = wear rate of 15 PPM per hour

93 ÷ 6.20 = wear rate of 15 PPM per hour

60 ÷ 4.00 = wear rate of 15 PPM per hour

The wear trend is consistent in this example, even though the drains and wear

numbers are not.