Hach ISENH4181 - Product Overview; Specifications

Section 1 Product overview
The Intellical ISENH4181 series probes are digital, combination ion-selective electrodes (ISE) that
measure the concentration of ammonium in water samples. The Ammonium Ionic Strength Adjuster
(ISA) does not adjust the pH of the sample. Thus, the probes measure the ammonium ion (NH
4
+
) but
not unionized ammonia (NH
3
). The probes have a built-in temperature sensor, a non-refillable gel
reference and non-replaceable membranes. Refer to Figure 1.
Figure 1 Probe overview
1 Sensing element 3 Sensor protection cap
2 Reference junction 4 Cable
Section 2 Specifications
Specifications are subject to change without notice.
Specifications Details
Probe type Digital combination probe with a non-refillable reference junction
and a built-in temperature sensor
Measurement range 0.018 mg/L (10
–6
M) to 9,000 mg/L (0.5 M) as ammonium
(NH
4
+
–N)
Accuracy ±0.02 mV or 0.05% (the larger value)
Sample pH range pH 0 to 8.5
Reference type Ag/AgCl
Reference junction Double junction (ceramic porous pin and annular porous PTFE)
Slope –58 mV/decade (90 to 110% at 25 °C (77 °F) in linear range per
Nernstian theoretical value)
Linear region 0.9 mg/L to 9,000 mg/L as ammonium
Temperature accuracy ±0.3 °C (±0.54 °F)
Temperature sensor type 30 kΩ NTC thermistor
Operating temperature 5 to 50 °C (41 to 122 °F)
Storage temperature 5 to 35 °C (41 to 95 °F)
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