Sulfur Sentry

This simple design by Envent Engineering utilizes a lead acetate based detection system that provides a linear and interference-free output of the H2S or optional Total Sulfur concentration.

  • Comes complete with a sample conditioning system
  • Rechargeable 12 volt battery operates independently for up to 24 hours with no external power source – battery charger included
  • Fast response times using Rapid Response Algorithm (RRA)
  • No interference from other components in the sample
  • Low power consumption <3 watts
  • Measures up to 5 times the calibrated range
  • Seven (7) day tape life
  • Quick delivery – as quick as 1 to 2 days for standard systems
  • Full field service & training available

Power 12-24 vdc @ less than 3 watts
Ambient Temperature 0-50˚C (32 to 122 F) Standard
Inlet Pressure 5 psig minimum to 1500 psig maximum.
34.48 kPa minimum to 10,342.5 kPa maximum.
Measuring Range 0-20 ppm to 0-200 ppm
Response time 20 seconds to alarm
Accuracy 1.5% of full scale, 1.5% repeatability
Inputs 4 digital inputs individually configurable.
Display 128 x 64 Graphic Display;
Menu is scrolled by push buttons.
Software A Windows® based program for archive retrieval is standard.
Analyzer Configuration software is available.
Dimensions 17.6″ L x 11.7″ W x 7.1″ D (44.7cm x 29.72cm x 18.03cm)
Weight 25lbs or 11.34 kg
* Product specifications subject to change without notice to improve reliability, function, design or otherwise.


The 331 measures H2S in natural gas or other process gases. The unit has dual 4–20 mA outputs, dual measurement alarms, plus trouble and fault alarm relays. The 331 displays H2S concentration in user specified units (ppb, ppm, grams, %, m/g3) and as well will auto range to 5 times the lower calibrated range. Calibration is performed manually via the operator interface or automatically when connected to a calibration bottle and optional auto calibration solenoid. The 331 is available with a number of sample systems and accessories to handle various applications such as high range H2S, Total Sulfur or H2S in liquids.

Lead Acetate Sensors: Lead acetate is essentially interference-free from other sulfur compounds. This is why it is used by the vast majority of industry users when accurate measurement is required. The linear output enables the user to perform a single-point calibration.

Longest Tape Life: Envent Tape is the strongest in the market, with the longest tape life by using a proprietary tape advance algorithm to make complete use of the 300-foot tape. The unit will accept up to a 350-foot roll.