Small-volume type Y or Z purging/pressurization system are enclosure pressurization or purging systems that operate on a supply of compressed instrument air or inert gas. It regulates and monitors pressure within sealed (protected) enclosures to prevent combustible dust accumulation, or remove and prevent flammable gas or vapor accumulations. Available in two models for enclosures with a maximum enclosure volume of up to 2 or 10 cubic feet (0.06 or 0.28 cubic meters). Includes tamper-proof regulator with gauge (TR-10G) to comply with NFPA standard requiring protection against overpressurization. Other purposes include heat, moisture and dust contamination prevention.