Dwyer® Durablock® series 250-AF inclined manometer air filter gages are designed using precision machining. The gages of 1" thick solid acrylic plastic are almost impossible to break and completely eliminate distortion.
Long-term accuracy is assured due to precision drilling of the fluid bore to ±.0002". The gages are prevented from any damaging or manipulation by a glass spirit level built in the body and encapsulated.
250-AF has a mirror chrome-plated brass scale. The scale aligns the meniscus with its reflection resulting in a reading free of parallax errors. Any fluid loss because of pressure surges is eliminated by the safety traps integrated in the body.
250-AF features "O" rings to positively seal the connection fittings. The fittings, however, are easily removeable for zeroing or fluid addition. These gages can be used in ambient temperatures of -20 to 150°F. Whenever there's a need for change of filter, indication is provided by red and green signal flags. The gages are delivered with complete instructions.
Two economy models, 451-AF and 452-AF, are available. These are same as the 250 Series, except not having over pressure traps.