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
803-150
PS-2 Pressure Sensor System
24 lbs.
