Accurate hydrogen sulfide analysis requires precise instrument calibration. The Jerome® 631-X and 631-XE hydrogen sulfide analyzers manufactured by Arizona Instrument LLC are factory calibrated using methods traceable to NIST (National Institute of Standards and Technology). The calibration system used at our manufacturing facility in Chandler, Arizona consists of the following components:
All Jerome® calibrations are performed in a climate controlled environment.
HYDROGEN SULFIDE GAS & MERCURY VAPOR SOURCE
AZI uses the VICI-Metronics DynacalibratorTM that contains a precisely controlled heat chamber and gas flow system. A small permeation tube of hydrogen sulfide or mercury is heated in the chamber. A tightly controlled air volume passes through the chamber carrying the gas to the test stations. The emission of hydrogen sulfide gas or mercury vapor from the permeation tube is a known value determined through successive measurements on an analytical balance. Internal meters that are calibrated to and verified against volume displacement bubble flow meters control airflow. The Dynacalibrators are calibrated regularly under our ISO 9001 guidelines by VICI-Metronics with methods traceable to the NIST.
The hydrogen sulfide vapor from the permeation tube exits the Dynacalibrator and passes into a 4 inch PVC manifold tube. This manifold prevents any positive or negative pressure from affecting the calibration process. This manifold chamber also allows multiple instruments to be calibrated at one time. Excess hydrogen sulfide is exhausted from the manifold through a charcoal trap.
Calibration of the Jerome® hydrogen sulfide analyzers is controlled through proprietary calibration software developed by Arizona Instrument LLC. Each unit passes through a rigorous calibration protocol to assure the unit’s accuracy, repeatability, and stability. A central computer that controls multiple units along the system manifold controls each step in the process.
The Jerome® gold film sensor is inherently stable and does not require frequent recalibration. We recommend an annual factory calibration. The interval between calibrations depends on instrument usage and operating conditions.
We recommend the use of the Jerome® FTM (Functional Test Module, part number Z2600-0918) to verify instrument operation between annual calibrations. The FTM introduces a known concentration of hydrogen sulfide into the Jerome® analyzer. When the results of this test fall within the expected range, the instrument is operating correctly. If the results are outside the expected range, the instrument should be considered out of calibration and returned to us. Continuous records of functional checks between annual factory calibrations verify the instrument’s operation and help satisfy regulatory requirements.
The flow of each Jerome® instrument is set to a precise rate prior to and during calibration. We use rotometers calibrated to a bubble flow meter, the primary standard for flow. Each flowmeter is calibrated on a regular basis with standards traceable to NIST. Calibration records for each flow meter are maintained under ISO 9001 guidelines.
Various electrical test points are measured with digital multimeters that are regularly certified and traceable to NIST. Calibration records for each multimeter are maintained under ISO 9001 guidelines.