Armstrong
จากประเทศ U.S.A.
วาล์วระบายอากาศ
21-AR—A small, high-quality economical air vent. It employs a single lever with a fixed pivot and viton seat, ensuring a tight shut-off.
21-312 AR/VAR —Forged steel version of the Model 21 with a larger float and higher leverage. Available with screwed, socketweld or flanged connections.
