Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 148, § 58

The board may make such rules and regulations as it deems suitable for the issuance of various types and classes of certificates for the following:

(a) a firm engaged in the business of servicing portable fire extinguishers or installing and servicing fixed fire extinguishing systems; (b) an employee of firms engaged in the business of servicing portable fire extinguishers or installing or servicing fixed fire extinguishing systems who services extinguishers or fixed systems; (c) a firm performing hydrostatic testing of fire extinguishers.

The provisions of this section shall not apply to the following:

(a) the filling or charging of a portable fire extinguisher by the manufacturer prior to its initial sale; (b) the servicing by a firm of its own portable extinguishers or fixed systems by its own personnel specially trained for such servicing; (c) the installation or servicing of water sprinkler systems installed in compliance with the State Building Code; (d) firms engaged in the selling at wholesale or retail of portable fire extinguishers but not engaged in the installation or recharging of them; (e) fire departments recharging portable fire extinguishers as a public service where no charge is made; provided, however, that the member of the fire department is trained in the proper filling and recharging of the fire extinguishers.