Evaluation of Low-Cost Hydrogen Sulfide Monitors for Use in Livestock Production

Abstract

Direct-reading gas monitors warn workers of the risk of potentially fatal hydrogen sulfide (H2S) exposures that may arise during manure handling. Low-cost, low-maintenance H2S monitors are available from many manufacturers, but differences in their features and performance make selection challenging for farmers. Moreover, little information is available on the practical maintenance and performance of these devices in agricultural environments. The objective of this study was to provide information to agricultural workers to aid in the selection, maintenance, and use of low-cost H2S monitors. This laboratory study evaluated the performance of several low-cost monitors over a simulated period of use of one year in a swine barn. Four models were exposed to H2S concentrations of 1 to 10 ppm over 18 weeks to examine the drift in reported concentration and changes in the alarm reaction time. Over the simulated barn year, the performance of alarm-only monitors declined faster than that of monitors displaying the H2S concentration. Of concern was the high-level (20 ppm) alarm failures after an equivalent of 139 days (Altair) and 289 days (BW Clip) in a swine barn, well within the monitor’s reported shelf-life. Models displaying concentration exhibited fewer failures but were inaccurate in the displayed concentration when challenged with 20 ppm of H2S. The T40 Rattler provided consistently higher readings (+2.3 ppm), and the Pac 3500 showed consistently lower readings (−3.4 ppm) when challenged with 20 ppm. This study confirms the need for routine bump tests for these low-cost monitors to ensure that the monitor reacts to the presence of H2S, even if the manufacturer does not recommend this procedure. Most importantly, agricultural workers should inspect and bump test these monitors prior to any potentially high-risk activity, such as manure agitation, pumping, or pressure washing, to ensure that the monitor appropriately detects and warns users.

Hydrogen sulfide monitor education for use in agricultural operations

“…Bump testing is challenging the monitor with a known concentration of H2S gas to make sure that the monitor is working correctly before using it in an unknown environment. In a previous study, monitors after being exposed to H2S the monitors took longer to respond to the H2S gas and failed bump tests (Beswick-Honn et al, 2017).…”

“…A 2017 study, conducted at the University of Iowa, identified monitors that may be better than their counterparts when used in an agricultural environment (Beswick-Honn et al, 2017).…”

“…During this study, four low-cost and low maintenance H2S monitors' performance were evaluated in a simulated agriculture environment (Beswick-Honn et al, 2017). All four monitors showed an increase in time it took for the monitor to respond to the H2S gas, compared to the monitors not exposed to H2S other than during bump testing (Beswick-Honn et al, 2017). When the monitor takes longer to respond to the gas, the farmer will also need wait longer for the concentration of H2S to be measured.…”

“…When the monitor takes longer to respond to the gas, the farmer will also need wait longer for the concentration of H2S to be measured. These monitors also failed bump checks much faster than the two-year guarantee provided by the companies, so this indicates the need for all monitors to be bump tested before use in an environment with H2S hazards (Beswick-Honn et al, 2017).…”

“…Videos demonstrating bump testing were generated, with website links etched into the display. The two monitors that were chosen for the display had to have the display showing concentration levels because in a recent survey, 89% of livestock producers reported that display concentration was an important feature for H2S monitors to have (Beswick-Honn et. al, 2017;Anthony, 2017).…”