41 CFR 102-39.25: -39.25 Conditions.

You may use the exchange/sale authority if:

(a) The property exchanged or sold is similar to the property acquired;

(b) The property exchanged or sold is not excess or surplus and you have a continuing need for similar property;

(c) The property exchanged or sold was not acquired for the principal purpose of exchange or sale;

(d) When replacing personal property, the exchange allowance or sales proceeds from the disposition of that property may only be used to offset the cost of the replacement property, not services; and

(e) When replacing personal property by sale, you must use the methods, terms, and conditions of sale, and the forms prescribed in part 102-38 of this subchapter.