through a drive shaft 144 the gearbox 136 of the present invention igms centrifugal blower is an integral part of the blower 100 which makes the blower 100 more compact and cost less than the conventional ddms with external gearbox arrangement the gear ratio of the present invention high pressure igms centrifugal blower 100 may range from 1 1 up to 2 1 or 3 1 so that the impellers 112 can rotate considerably faster than those of the conventional ddms the increased impeller speed increases the pressure generated by the impellers 112 and requires fewer stages to reach the same pressure this results in the reduction of the weight and size of the blower 100 the higher speed capability of the present invention high pressure igms centrifugal blower 100 also increases the blower efficiency by utilizing more efficient backward curved impellers 112 in place of conventional less efficient radial impellers the use of backward curved impellers 112 have a steeper performance curve which enhances the control capability when coupled with a piping system to adjust for 50 hz applications the present invention igms 100 may utilize a 1 2 1 higher ratio gear so that the impeller speed can be raised to the same level as in the 69 hz application since the speed of igms centrifugal blower is considerably lower than conventional igss blowers standard rolling element bearings 116 and simple splash lubrication system 144 can still be utilized and the low cost manufacturing requirements of traditional ddms can still be applied which result in a substantial.