Section R. 408.17224 - Ventilation and air receiversRule 7224.
(1) Ventilation shall be provided and used to exhaust toxic vapors or fumes if such vapors or fumes exceed the maximum allowable limits prescribed by a department of public health rule.(2) The blades of a fan less than 7 feet from a floor, platform or ground shall be guarded on all sides. Openings in a guard shall be not more than 1 inch and the distance shall be not less than the values in table 1.(3) A fan shall not be located where fumes of flammable liquids can be induced into an area where sparks or flame may be present.(4) An air receiver shall be equipped with an operable relief valve set at not more than the working load limit of the receiver. Table 1
| Smallest dimension in guard (in): | Minimum distance from guard to blade |
| Greater than 0 up to 1/4 inclusive. | 1/2 inch |
| Greater than 1/4 up to 3/8 inclusive. | 1 1/2 inches |
| Greater than 3/8 up to 1/2 inclusive. | 2 1/2 inches |
| Greater than 1/2 up to 3/4 inclusive. | 4 inches |
| Greater than 3/4 up to 1 inclusive | 6 times the smallest dimension |
Mich. Admin. Code R. 408.17224