US VTP-99 VERTICAL TRANSIT RATE PACER

HIF/FISP Part # 4110032

The US VTP-99 vertical transit rate pacer is a commercially manufactured electronic programmable metronome. It provides an audible time-interval reference for pacing the lowering and raising of a suspended-sediment sampler when collecting depth-integrated samples. The audible signal eliminates the use of a stopwatch.

The uniformity of the vertical speed of a sampler directly affects the accuracy of depth-integrated samples. The pacer makes uniform vertical rates possible and therefore helps to ensure an accurate flow-weighted sample. Any operator may reproduce a given vertical rate at any time and at any location. Reproducibility is particularly important when collecting samples using the ETR (equal-transit-rate) method.

The pacer may be used with handheld samplers as well as mechanically hoisted samplers. The small size permits carrying the device in a shirt pocket. The tone is audible for several feet so that in a quiet environment a headphone is not required. The US VTP-99 has a miniature phone type monaural headphone jack. Headphones are not supplied.