GrayWolf Sensing Solutions, LLC is a manufacturer of professional environmental measurement instruments, founded in 1998 and based in the United States and Ireland with worldwide distribution and service. The company designs and builds high-performance portable, datalogging, and long-term fixed monitors used to measure indoor air quality (IAQ), volatile organic compounds (VOCs), toxic gases, airborne particulate, and HVAC parameters such as airflow and differential pressure.
For more than 25 years GrayWolf has focused primarily on the indoor air quality market while also supplying toxic-exposure sensing instruments to occupational hygienists, industrial hygiene (IH) professionals, building scientists, test, inspection and certification (TIC) professionals and researchers. Its instruments are used across commercial, industrial, institutional, government, and research settings — from schools, hospitals, and office buildings to manufacturing plants, laboratories, and shipboard environments.
GrayWolf instruments measure a broad range of air quality and environmental parameters, typically several at once. Core measurement categories include:
Measured values can be displayed and logged in the user’s choice of units where applicable — parts per billion (ppb), parts per million (ppm), micrograms per cubic meter (µg/m³), milligrams per cubic meter (mg/m³), and percent (%). Factory calibration is stored on each smart sensor, and calibration certificates are provided; NIST-traceable calibration is available for most sensors, and user calibration kits allow on-site/field recalibration.
The following gas and vapor sensors are available for the GrayWolf DirectSense XM / DirectSense II smart probes which are equipped as standard with Temperature and Relative humidity sensors. Up to six user-exchangeable smart sensors can be configured in a single probe for a total of eight parameters. Multiple probes can be used simultaneously, and multiple ranges are offered for some parameters (for example TVOCs, Ammonia, and CO2) so the instrument can be optimized for low-level detection for indoor air quality work or for higher-level detection for toxic-exposure applications.
| Measurement parameter | Measurement range | Sensing technology |
| Carbon Dioxide (CO2) | 0 to 10,000 ppm | NDIR |
| TVOC — low (ppb) range | 0 to 40 ppm | PID (10.6 eV) |
| TVOC — mid-low range | 0 to 200 ppm | PID (10.6 eV) |
| TVOC — mid-high (ppm) range | 0 to 4,000 ppm | PID (10.6 eV) |
| TVOC — high (ppm) range | 0 to 10,000 ppm | PID (10.6 eV) |
| Ammonia (NH3) | 0 to 100 ppm | Electrochemical |
| Ammonia (NH3) — high range (TOX) | 0 to 1,000 ppm | Electrochemical |
| Arsine (AsH3) | 0 to 1 ppm | Electrochemical |
| Carbon Monoxide (CO) | 0 to 500 ppm | Electrochemical |
| Chlorine (Cl2) | 0 to 20 ppm | Electrochemical |
| Chlorine Dioxide (ClO2) | 0 to 1 ppm | Electrochemical |
| Diborane (B2H6) | 0 to 1 ppm | Electrochemical |
| Ethylene Oxide (EtO) | 0 to 100 ppm | Electrochemical |
| Fluorine (F2) | 0 to 1 ppm | Electrochemical |
| Formaldehyde (HCHO) | 0 to 1 ppm | Electrochemical |
| Hydrogen (H2) | 0 to 1,000 ppm | Electrochemical |
| Hydrogen Chloride (HCl) | 0 to 20 ppm | Electrochemical |
| Hydrogen Cyanide (HCN) | 0 to 100 ppm | Electrochemical |
| Hydrogen Fluoride (HF) | 0 to 10 ppm | Electrochemical |
| Hydrogen Sulfide (H2S) | 0 to 50 ppm | Electrochemical |
| Nitric Oxide (NO) | 0 to 250 ppm | Electrochemical |
| Nitrogen Dioxide (NO2) | 0 to 20 ppm | Electrochemical |
| Ozone (O3) | 0 to 1 ppm | Electrochemical |
| Phosgene (COCl2) | 0 to 1 ppm | Electrochemical |
| Phosphine (PH3) | 0 to 10 ppm | Electrochemical |
| Silane (SiH4) | 0 to 50 ppm | Electrochemical |
| Sulfur Dioxide (SO2) | 0 to 50 ppm | Electrochemical |
| Oxygen (O2) | 0 to 25 % | Electrochemical |
Resolution, limit of detection, and T90 response time are published for each sensor in GrayWolf’s full Smart Sensor Specifications document. Additional gases are added to the range over time.
The DirectSense XM model DSXM-8 (and the earlier DirectSense II) is a smart, multi-sensor probe that holds up to six user-swappable plug-and-play sensors in a single unit plus temperature and relative humidity for a total of eight parameters. Sensors store their own factory calibration, so users can change them on-site to suit the application or send individual sensors for recalibration. The probe can store months of logged data onboard and connects by cable, Bluetooth LE, or Wi-Fi. Lower-capacity versions (DSXM-5 and DSXM-3) are available when fewer gas sensor slots are needed.
The AdvancedSense XM is GrayWolf’s purpose-built handheld meter and datalogger. It supports up to 32 simultaneous parameters, connecting one or more DirectSense XM probes — plus particle meters and other internal and external sensors — by cable or Bluetooth LE, and can publish readings to the cloud over Wi-Fi. The AdvancedSense XM also has an optional integrated differential pressure micromanometer, K-Type Thermocouple sockets and a barometric pressure sensor for reading compensation. Hard-shell security cases support unattended long-term trend logging.
GrayWolf offers particle meters (such as the PC-3016A and PC-3500) measuring multiple size channels from 0.3µm to 10.0µm and PM 2.5, PM 10.0 and Total Particulate (TPM). The Particulate Meters can be interfaced with AdvancedSense XM Meters, Tablets, Mobile Phones or used as stand-alone meters.
GrayWolf offers telescoping hot-wire anemometers and unique extendable Pitot-static tubes, and differential-pressure micromanometers including the Zephyr XM meter.
GrayWolf instruments are used for indoor air quality and indoor environmental quality (IEQ) surveys, green-building certification testing, toxic-gas and occupational-exposure monitoring, HVAC commissioning and ventilation assessment, and research. Specific applications include:
GrayWolf’s instruments are used by government agencies, aerospace and aviation organizations, universities and medical research institutions, architecture and construction firms, and industrial manufacturers worldwide. Customers named on the company’s site include NASA, Boeing, Airbus, the U.S. EPA, U.S. OSHA, NIST, the U.S. FDA, Harvard Medical, MIT, Yale, Intel, Siemens, Pfizer, GlaxoSmithKline, Bureau Veritas, and the United Nations, among many others.
“Our agency has utilized GrayWolf devices for several decades…
Their state-of-the-art technology has empowered us to identify airborne hazards with precision.”
— Derek J. Falzoi, CIH, Architect of the U.S. Capitol
Manufacturer of Indoor Air Quality, VOC, Toxic Gas, Particulate, and HVAC measurement instruments since 1998.
