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4250 Flow Meter
Area Velocity - no
weir or flume needed! Handles submerged, surcharged, and reverse flow.
 The
sensor on the Isco 4250 uses patented Doppler technology to directly measure
average velocity in the flow stream. An integral pressure transducer measures
liquid depth to determine flow area. The 4250 then calculates flow rate by
multiplying the area of the flow stream by its average velocity.
The 4250 gives you greater accuracy in applications where weirs or flumes are
not practical, or where submerged, full pipe, surcharged and reverse flow
conditions may occur. With area velocity you don’t have to estimate the slope
and roughness of the channel. And Isco’s exclusive 500 kHz Doppler penetrates
farther into deep flow streams than 1 MHz systems, whose shorter wavelength can
cause them to give “nearsighted” velocity measurement in typical wastewater
applications. The Doppler system continuously profiles the flow stream,
eliminating profiling and calibration required by electromagnetic systems.
Standard Features
- 4200 Series
- Built-in flow conversions for most applications, including Manning
formula, data points, or equation for special situations.
- Set up with or without a computer. All setup functions can be done either
via onboard keypad and two-line x 80-character backlit LCD, or by connection
to PC with Flowlink software.
- Built-in dot matrix printer gives you an accurate, on-site printout
- Internal memory stores over 2 months of flow, rainfall, parameter, and
sample data at 15 minute intervals.
- Outputs for Sampler activation, alarm outputs
- Inputs for connection to 674 Rain Gauge and multiparameter water quality
sonde,
- 4250 Area Velocity
- Sealed Area-Velocity sensor resists fouling by oil and grease. Streamlined
shape sheds debris.
- Choice of standard (10 ft) and extended (30 ft) level measurement range.
Applications
- Accurate open channel flow measurement without a weir or flume
- Pretreatment Compliance
- Stormwater Runoff Monitoring
- Permit Enforcement
- Sewer Flow Monitoring
- Combined Sewer Overflow Studies
- Inflow and Infiltration Studies
- River and Stream Gauging
Options and Accessories
- Choice of Standard and Low Profile Area Velocity Sensors.
- Standard Sensor is recommended for larger pipes and turbid flows with high
concentrations of suspended solids and entrained air.
- Low Profile Sensor is recommended for shallows flows, typically down to
1" (25 mm).
- Optional telephone modem - provides remote data retrieval, voice
messaging, and dial-out alarm conditions
- Analog Outputs - up to 3 isolated internal 4-20 mA outputs
- Mounting rings for installation of probe in round pipes from 6 to 15
inches in diameter
- Non-resettable totalizer
- 674 Rain Gauge
- 581 RTD data retrieval device downloads up to 20 meters
- 270 DO module adds dissolved oxygen measurement/logging
- 201 pH module adds pH and temperature measurement/logging
- YSI 600 Multi-Parameter Water Quality Monitor
- Suspension equipment (to hang flowmeter in manhole)
Specifications
| Size (H x W x
D): |
17.0 x 11.5 x
10.5 in. (43 x 29 x 26.7 cm) (without power source) |
| Weight: |
17.3 lbs (7.8
kg) (without power source) |
| Material: |
High-impact
molded polystyrene structural foam |
| Enclosure: |
NEMA 4X (iP65) |
| Power: |
12 to 14V DC, 14
mA average at 12.5V DC |
| Typical
Battery Life (printer set at 1 in/hr, 1 minute level reading interval, 5
minute velocity reading interval) |
| 934
Nickel-Cadmium Battery: |
8 to 11 days |
| 946 Lead-Acid
Battery: |
12 to 16 days |
| 948 Lead-Acid
Battery: |
2˝ to 3 months |
| Program Memory: |
Non-volatile,
programmable flash. Updateable without opening enclosure. |
| Display: |
Backlit LCD,
2-line, 80-character (5.5 mm high x 3.2 mm wide) |
| Level-to-Area
Conversions |
| Channel shapes: |
Round, U-shaped,
rectangular, trapezoidal |
| Data points: |
Four sets of 50
level-area points |
| Level-to-Flow
Rate Conversions |
| Weirs: |
V-notch,
rectangular, Cipolletti |
| Flumes: |
Parshall,
Palmer-Bowlus, Leopold-Lagco,Trapezoidal, H, HS, HL |
| Manning Formula: |
Round,
U-channel, rectangular, trapezoidal |
| Data Points: |
Four sets of 50
level-flow rate points |
| Equation: |
Two-term
polynomial |
| Totalizers |
| LCD: |
Total, forward,
and reverse flow; 9 digits each, floating decimal point, resettable |
| Mechanical
(optional): |
Total flow, 7
digits, non-resettable |
| Area
Velocity Sensor (See separate specifications for low-profile sensor) |
| Size (LxWxH): |
6.6 x 1.6 x 1.2
inches (16.8 x 4.1 x 3.0 cm) |
| Weight, incl.
cable: |
2.1 lbs (0.96
kg) for standard probe with 25 foot cable; 3.9 lbs (1.8 kg) for extended
range probe with 50 ft cable. |
| Ambient
Operating Temperature Range: |
0° to 140°F
(-18° to 60°C) |
| Compensated
Temperature Range: |
32° to 140°F
(0° to 60°C) |
| Materials: |
Polybutadiene-based
polyurethane, stainless steel; PVC and CPVC cable |
| Velocity
Measurement |
| Method: |
Doppler
Ultrasonic, 500 kHz |
| Velocity range: |
-5 to +20 ft/s
(-1.5 to 6.1 m/s) |
| Level
Measurement |
| Method: |
Submerged
pressure transducer |
| Standard range
probe: |
measurement
range 0.05 to 10 ft (0.015 to 3.05 m); max level 20 ft (6.1 m) |
| Extended range
probe: |
measurement
range 0.05 to 30 ft (0.015 to 9.1 m); max level 40 ft (12.2 m) |
| Standard
probe accuracy (Non-linearity, repeatability, and hysteresis at 25°C
(77°F). Max error for indicated level range. |
| 0.05 to 5 ft
(0.015 to 1.52m): |
±0.01 ft (±0.003
m) |
| 0.05 to 7 ft
(0.015 to 2.13m): |
±0.03 ft (±0.009
m) |
| 0.05 to 10ft
(0.015 to 3.05m): |
±0.1 ft (±0.03
m) |
| Extended
probe accuracy (Non-linearity, repeatability, and hysteresis at 25°C
(77°F). Max error for indicated level range. |
| 0.05 to 15ft
(0.015 to 4.57m): |
±0.03 ft (±0.009
m) |
| 0.05 to 21ft
(0.015 to 6.4m): |
±0.09 ft (±0.027
m) |
| 0.05 to 30ft
(0.015 to 9.14m): |
±0.3 ft (±0.09
m) |
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