Plumbing your shop or hangar for compressed air is money well spent.
Use iron pipe, the size selected according to the run & volume. This
should be defined by your local building codes.

All runs should slope TOWARD the compressor. That is,any water would
have to run UPHILL to find an outlet.

Do not use copper nor plastic.

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Blasting media is also subject to contamination by moisture. It
should be stored in air-tight containers. In the worse-case situation
it may need to be dried before it can be used, a hell of a mess
involving an oven and trays. For small parts you may wish to consider
tumbling rather than blasting.

-R.S.Hoover