PS-2 Pressure Sensor System

The USGS Standard Nonsubmersible Pressure Sensor (PS) system, the PS-2, works with a USGS gas-purge (bubbler) system and data logger or data-collection platform to measure and record water level in feet of stage by using a gas-purge system to transmit the pressure head of water over an orifice to the pressure transducer. The PS-2 is specifically designed for water level measurements to meet the U.S. Geological Survey Specification HIF-S-02.

PS-2's are certified to measure pressure over the range of 0 to 30 pounds per square inch gage with a total error less than ±0.02 percent of full scale. This corresponds to a range of 0 to approximately 70 feet of water with an error of less than ±0.01 foot of water. The PS-2 comes in three standard models. The PS-2-30 (30 feet of water, 10 meters), P-2-50 (50 feet of water, 16 meters) and the PS-2-70 (70 feet of water, 20 meters). The units are temperature compensated to operate within the specified accuracy at any temperature within the range of -20 to 55 degrees C.

The PS-2 is housed in an 8 by 10 by 6 inch fiberglass environmental enclosure with mounting feet for attaching to a wall or bench (see fig. 2). It consists of an Aquabar Model 9300 pressure transducer, pressure transmitter, and associated plumbing and wiring. A 4-pin connector is provided for electrical connection to the SDI-12 bus and external 12-volt power. The pressure transmitter is equipped with a relief valve for protection from overpressure resulting from either improper purging of the orifice line or a clogged orifice. A gas connection kit, with instructions, is provided for connecting the PS-2 to an existing gas-purge system. The PS-2, ready to install, weighs approximately 6 pounds and comes with mounting feet for securing it to a bench, table or wall.

The PS-2's come standard with the SDI-12 (serial digital interface) developed by the USGS but is also available with standard computer serial RS-232, 16 bit parallel interface port. This enables the pressure sensor system to be used with any industry standard data logger and personal computer.

The PS-2's record these values at every user-selected interval:

Time

Water level (feet or meters)

Pressure transducer temperature (approximate shelter temperature)

In addition to the above recordings, the PS-2 system records these values at midnight:

Year

Date (previous day)

Maximum reading (last 24 hours)

Minimum reading (last 24 hours)

Battery voltage

SDI-12 or RS-232C Interface Communications

 The SDI-12 (Serial Digital Interface - 1200 baud) was developed by the USGS as a result for a demand for simple, low-powered serial digital interface that is capable of having multiple microprocessor-based sensors connect to a single datalogger. This interface, primarily used for hydrologic and environmental sensors and requires only 3 wires for proper communications: power, data and ground. The transmitter receives commands from a data logger or user computer via the data bus and returns data via the same bus. The data bus is a 1200 baud serial ASCII multi-drop two-wire data bus using 0 to 5 volt logic levels. The PS-2 water level systems are offered with this SDI-12 output, making ideal instruments for remote, battery-powered water staging operations. The SDI-12 version can be converted to RS-232C output with a simple external data converter.

RS-232C

The PS-2 System is also available with RS-232C output, in a selectable baud rate of 300, 1200, 2400, or 9600. Therefore using the included mating cable, virtually anyone can connect the units directly to a computer, laptop or datalogger and begin measuring water level or pressure. Basic user's software is provided as well as simple command instructions to enable user-written custom programs.

The complete PS-2 Pressure Sensor System comes with the following components:

Model 9300 Aquabar non-submersible vented pressure transducer enclosed in a sealed case - specify range in feet or meters

USGS Bubbler Gas-Purge system. Included in the PS-2 gas-purge system are the Conoflow sight feed, regulator, and pressure hose, black orifice tubing and standard orifice w/static tube.

Model CR510 Datalogger with on-site display of data

12 volt battery, 24 amp-hr battery capacity