Note On The Use of Watch Jewels as Critical Flow Orifices

Evaluation of a flushing-gutter manure-removal system to improve atmospheric quality in housing for laying hens

“…As the pressure drop across an orifice increases, the flow rate through the orifice increases until the gas velocity at the throat becomes sonic. Any further increase in the pressure drop across the orifice will not cause any increase in the flow rate (Brenchley, 1972). This allows a constant flow rate to be maintained with a variable vacuum source as long as sufficient vacuum is developed to maintain sonic velocity in the orifice throat.…”

“…Limited-flow orifices can be purchased commercially, or other manufactured items can be calibrated, such as hypodermic needles, watch jewels, or glass capillaries (Brenchley, 1972;Huygen, 1970;Lodge et al, 1966). Before the arrival of the commercial orifice used during the majority of the sampling described, hypodermic needles were calibrated for sampling.…”

Evaluation of a flushing-gutter manure-removal system to improve atmospheric quality in housing for laying hens

“…an orifice increases, the flow rate through the orifice increases until the gas velocity at the throat becomes sonic. Any further increase in the pressure drop across the orifice will not cause any increase in the flow rate (Brenchley, 1972). This allows a constant flow rate to be maintained with a variable vacuum source as long as sufficient vacuum is developed to maintain sonic velocity in the orifice throat.…”