The Lo-Loss flow meter (Figure 500-21) is a proprietary design of Badger Meter Inc. (Tulsa, OK). Figure 500-22 shows a plan view of a PMT Lo-Loss flow meter.
The Lo-Loss flow meter is a modification of the venturi design. The major advantages of the Lo-Loss are as follows.
• It produces high differentials with lower permanent pressure loss. This high pressure recovery feature can greatly enhance operating economy.
• It is lower in weight.
• It requires shorter overall laying lengths.
Several designs are available. Construction materials vary from exotic alloys to cast iron and plastic. Selection of material is based on operating temperature and fluid type.
The accuracy of uncalibrated Lo-Loss flow meters is claimed to be ±0.75% of rate. Calibrated meters may achieve ±0.25%—according to Badger Meter. The manufacturer should be consulted for help in sizing and specifying a Lo-Loss flow meter. Outside the U.S.A., a similar meter called “Dall Tube” is also available.