Classification of a wide range indicator
Pipeline and Hazardous Materials Safety Administration · Sep 4, 2008 · Reference No. 08-0195
Interprets: 49 CFR § 173.4
Reggie’s quick take
A company asked whether a wide range pH indicator, sold in a 30 ml bottle packed in a kit, counts as a flammable liquid. The agency said yes: it is a Class 3, Packing Group II flammable liquid. Because the bottle is small, it can use the small-quantity exception in § 173.4 when packed as described, with the bottle in a plastic bag inside a kit case and a fiberboard box marked under that section.
Written by AI (Claude) on Oct 22, 2026. Robots make mistakes and leave things out, so the letter below is what counts. Not legal advice.
This is in response to your July 17, 2008 letter requesting clarification on the proper classification of a wide range indicator under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you request confirmation of your understanding that your wide range indicator meets the definition of a Class 3 (Flammable liquid) material and the small amount of 2,4 Dinitrophenol, wetted does not contribute to the hazard of the solution. According to your letter, the wide range indicator is used to determine the pH of water samples. The wide range indicator is shipped in a 30 ml bottle and is packed with other non-hazardous materials in a kit.
According to the material safety data sheet included with your letter, the wide range indicator is comprised of the following:
" 52 % Ethyl Alcohol
" 2 % Methyl Alcohol
" 0.5 % Sodium hydroxide
" 0.05 % 2,4 Dinitrophenol, wetted
" <0.1 % Phenolpthalein
" <0.5 % various non-hazardous dyes
" Water comprises the remainder of the solution
You state that the wide range indicator is contained in a 30 ml plastic bottle. The bottle has a dropper tip plug, a screw cap over the plug and shrink band tape secures the cap. The bottle is placed into a plastic bag within a kit case. The kit case is placed into a fiberboard box with cushioning material and the fiberboard box is marked in accordance with § 173.4.
It is the opinion of this Office that the wide range indicator described in your letter, meets the definition of a Class 3, flammable liquid, Packing Group II and may utilize the exception provided in § 173.4 applicable to small quantities.
I hope this answers your inquiry.
A letter of interpretation applies the regulations to the facts the requester described. It isn’t a regulation and isn’t legal advice. The agency’s copy.