Arsine Detectors Compared: RKI FP-301 Tape Monitor vs Sensidyne Detector Tubes

An arsine detector has to read far below 1 ppm, because the exposure limits that matter run from about 0.6 ppb (NIOSH ceiling) to 50 ppb (OSHA 8-hour limit). ERE carries two ways to measure arsine: the RKI FP-301 paper-tape monitor, and Sensidyne colorimetric tubes, the arsine tube (GIL-140SA) and the phosphine and arsine tube (GIL-121U). This guide lines each published range up against the published limits, so you can see which one can actually answer your question. All sit within our portable gas detectors range.

In this guide

• What arsine levels does a detector need to resolve?
• Which arsine detector can read each limit?
• When is the FP-301 tape monitor the right tool?
• When are detector tubes enough?
• How do I choose an arsine detector, step by step?
• Frequently asked questions

What arsine levels does a detector need to resolve?

From well under 1 ppb up to about 3 ppm. Arsine (AsH3) is a colourless gas with a mild garlic-like odour, and NIOSH lists blood, kidneys and liver as target organs and treats it as a potential occupational carcinogen (NIOSH Pocket Guide). The published reference levels:

*Our arithmetic: NIOSH gives 1 ppm = 3.19 mg/m³, so 0.002 mg/m³ is about 0.00063 ppm. The ACGIH publishes its own TLV for arsine; OSHA's chemical database points to ACGIH for the current value, and the FP-301 record cites it, so confirm the current number with ACGIH. Canadian jurisdictions each set their own limits, and CCOHS lists the legislative references. Confirm the limit that applies to your site before choosing a range.

Which arsine detector can read each limit?

Only the FP-301 works at the low end, and no ERE instrument spans the whole ladder. The table compares each published range against each level (our comparison from the ERE product records, not a manufacturer claim):

Two consequences. First, the FP-301 alarms on the low-level question, but its 15 ppb full scale means a release at the OSHA limit (50 ppb) would be off-scale; treat it as an early-warning monitor, not a measurement of a large leak. Second, the IDLH of 3 ppm sits in a gap between the 121U (2 ppm top) and the 140SA (5 ppm bottom), so for emergency-level measurement ask us about the right tube or instrument rather than assuming one tube covers it.

When is the FP-301 tape monitor the right tool?

When you need continuous, interference-free ppb detection at a fixed point such as a scrubber exhaust or fab environment. From the ERE record for the RKI FP-301:

• A replaceable colorimetric tape specific to arsine (AsH3) and hydrogen selenide (H2Se); ranges of 0-15 ppb AsH3 and 0-200 ppb H2Se.
• A digital display of gas type and concentration in ppb, remaining tape life, and an end-of-tape alarm.
• Audible and visual alarms at two levels, alarm relay contacts and a 4-20 mA output.
• A "tape saver" mode for high-background applications; the record says it does not respond to hydrocarbons, alcohols, solvents or CO.
• Operating temperature 5-35 °C; panel version 24 VDC or desktop version 100-220 VAC. The listed applications are uncaptured gas from a scrubber and environmental monitoring in semiconductor fabs.

The record states the unit "meets and exceeds OSHA and NIOSH compliance requirements"; that is the supplier's wording, so check it against your own regulator. Tape cassettes are a consumable you reorder. Pricing is quoted on request.

When are detector tubes enough?

For spot checks, leak response and clearance testing at or above the OSHA level. OSHA's own database lists detector tubes with the same model numbers (121U, 140SA) as on-site screening techniques for arsine. The two Sensidyne tubes ERE lists:

The 121U is listed as a phosphine and arsine tube, so confirm which gas is present before reading a stain as arsine. Tubes give one reading per sample with a hand pump and no alarm. Our gas detection tubes guide explains how to read and store them. For a similar comparison on another toxic gas, see our formaldehyde detector guide.

How do I choose an arsine detector, step by step?

1. Write down the target. A ppb-level environmental limit, the OSHA 50 ppb level, or an emergency threshold.
2. Check the range against the target. A tube whose bottom end equals your limit can only confirm exceedance, not prove compliance.
3. Pick continuous or spot. A scrubber exhaust or fab space points to the FP-301; leak checks and clearance point to tubes.
4. Plan consumables. Tape cassettes for the FP-301, single-use tubes for the pump.
5. Plan the alarm path. The FP-301 has relay contacts and 4-20 mA; tubes have none. For fixed systems see our fixed gas detectors guide.
6. Plan upkeep. Ask about calibration and servicing when you request a quote; see gas detector calibration in Canada and our portable gas detector buyer's guide.

Frequently asked questions

What range does an arsine detector need?

Low-ppb to low-ppm. NIOSH's ceiling is about 0.63 ppb, OSHA's 8-hour limit is 0.05 ppm (50 ppb) and the IDLH is 3 ppm.

Can a detector tube measure arsine at the OSHA limit?

Only at its lower edge. The 121U tube range starts at 0.05 ppm, which equals the OSHA 8-hour limit, so it confirms exposure at or above that level but cannot show compliance below it.

What does the RKI FP-301 detect?

Arsine (AsH3) and hydrogen selenide (H2Se), using a colorimetric tape. The ERE record lists 0-15 ppb for AsH3 and 0-200 ppb for H2Se, with alarm relays and a 4-20 mA output.

Is arsine toxic?

Yes. NIOSH lists blood, kidneys and liver as target organs and gives an IDLH of 3 ppm. Follow your site's gas-handling procedures and the limits that apply to you.

Does ERE sell arsine detectors in Canada?

ERE lists the RKI FP-301 and Sensidyne arsine and phosphine-arsine tubes. Pricing and availability are given on request.

Related articles

• Gas Detection Tubes: A Buyer's Guide for Canada
• Portable Gas Detectors: A Buyer's Guide for Canada
• Fixed Gas Detectors: A Buyer's Guide for Canada
• Formaldehyde Detectors Compared for Canada

Lire en français : Détecteur d'arsine : moniteur à ruban FP-301 ou tubes Sensidyne