

IS-Max™ flow meter (for Class I Division 1)
Mass flow measurement where explosive gases are continuously present
Flow meters for Class I Division 1 environments provide precise gas measurement where explosive gases are continuously present. IS-Max is an intrinsically safe device certified for Zone 0 with ATEX, IECEx and North American DEKRA approvals, ensuring compliance in hazardous areas.
Using laminar differential pressure technology, IS-Max delivers accurate mass and volumetric flow measurement with multivariable reporting, including temperature and pressure data.
Key features:

| Certification | Marking | Certificate |
|---|---|---|
| ATEX | II 1G Ex ia IIC T4 Ga Tamb -20 °C to +70 °C | DEKRA 22ATEX0075X |
| IECEx | Ex ia IIC T4 Ga Tamb -20 °C to +70 °C | IECEx DEK 22.0078X |
| North America | Class I, Division 1, Groups A-D T4, Ex ia Class I, Zone 0, AEx ia IIC T4 Ga Tamb -20 °C to +70 °C | DEKRA 23CAUS40-127215 |
| Range | 0.5–5 SCCM | 10 SCCM – 20 SLPM | 40–1000 SLPM |
|---|---|---|---|
| Mass flow accuracy | Standard accuracy: ± 0.8% of reading and ± 0.2% of full scale High accuracy: ± 0.4% of reading and ± 0.2% of full scale (5 SCCM only) | Standard accuracy: ± 0.75% of reading or ± 0.1% of full scale, whichever is greater High accuracy: ± 0.6% of reading or ± 0.1% of full scale, whichever is greater | Standard accuracy: ± 0.8% of reading and ± 0.2% of full scale High accuracy: ± 0.4% of reading and ± 0.2% of full scale |
| Flow repeatability (2σ) | ± 0.2% of reading and ± 0.02% of full scale | ± 0.1% of reading and ± 0.02% of full scale | ± 0.2% of reading and ± 0.02% of full scale |
| Pressure sensitivity | Mass flow zero and span shift: ± 0.08% of reading ± 0.02% of full scale per atm from calibration conditions | Mass flow zero shift: ± 0.01% of full scale per atm from tare pressure Mass flow span shift: ± 0.1% of reading per atm from calibration conditions | Mass flow zero and span shift: ± 0.08% of reading and ± 0.02% of full scale per atm from calibration conditions |
| Parameter | |
|---|---|
| Pressure accuracy | Above 1 atm: ± 0.5% of reading Below 1 atm: ± 0.07 PSIA |
| Flow measurement range | 0.01–100% of full scale (10,000:1 turndown) |
| Operating pressure | 11.5–60 PSIA |
| Temperature sensitivity | Mass flow zero shift: ± 0.03% of full scale per °C from tare temperature Mass flow span shift: ± 0.01% of reading per °C from 25 °C Mass flow zero and span shift: ± 0.03% of full scale per °C from 25 °C |
| Temperature accuracy | ± 0.75 °C |
| Relative humidity accuracy | ± 1.8% RH at +23 °C (0% RH … 90% RH) |
| Relative humidity temperature sensitivity | 0.05% RH/°C (0 °C … +60 °C) |
| Operating temperature range | -20…70 °C (ambient and gas) |
| Total volumetric uncertainty | ± 0.1% of reading (additional uncertainty) |
| Sensor response time | < 1 ms |
| Typical indicator response time | 127 ms, user adjustable |
| Typical warm-up time | < 1 s |
For detailed information on all flow meter models, contact our laboratory installation consultants.
Datasheets (Alicat):
