Sample Quality| Industrial hygiene & Environment | Safety

Liquid and Gas Sampling  

Fuming Acids Sampling (Sulfuric Acid H2SO4, Oleum, Sulfur Trioxide SO3) Project

At Biar Inc., we specialize in developing sampling valves that provide samples with the highest level of purity while safeguarding the operator against any hazards that could result from contact with the sampling chemical. A major chemical manufacturer contacted our team to create a sampling valve capable of sampling fuming acid compounds. Prior to contacting us, the customer that we designed this valve for had been using an inferior sampling method that did not result in a pure sample and presented several safety risks.

Fuming acids such as sulfuric acid, sulfur trioxide, and chlorosulfonic acid are used extensively in the manufacturing of chemicals used in personal care items, tire cord adhesive, and laminated lumber products, fire retardants, and pharmaceuticals. While fuming acids are not considered lethal in small amounts, contact with skin can cause corrosion, burns, or ulcers and these acids react with moisture present in the air to form a visible sulfuric acid mist. Therefore, while trace amounts may be vented into the atmosphere, the valve must protect the operator from contact with skin, eyes, or clothing. Additional caution must be taken when selecting the valve material, as stainless steel reacts with sulfuric acid to cause excessive corrosion and form sulfate compounds, which can plug small diameters.

Taking these safety and sampling considerations into account, we developed a solution that consists of a multi-function PFA lined valve with an integrated vent connection, spring to close hand wheel, thread adapter, and safety plug. Since stainless steel is problematic when working with fuming acids, an aluminum valve was manufactured and coated with a PFA (PTFE) lining. The size of the valve is unusual for an aluminum enclosure, so the actual manufacturing of the valve provided a challenge. We employed several advanced manufacturing processes, including CNC turning, sinker electrical discharge machining, laser drilling, and TIG welding, to create the sampling system assembly.

When possible, most laboratories prefer bottles as the sampling vessel over manufacturer’s proprietary containers, due to their ease of use. Because a bottle sampling vessel was desired, a vent was integrated into the design that vented any fumes away from the operator during sample collection. This method of collection proved to be acceptable provided that proper ventilation was available during sample collection, the sampling temperature did not exceed 140° F, and the sampling pressure did not exceed 50 psi. The spring to close actuator, or Magic Hand Wheel, prevents overflow of the sample if the operator’s hand slips from the valve, and the safety plug acts as a secondary containment mechanism when the valve is not in use.

Our multi-function valve design allows the customer to easily remove the adapter for cleaning as often as desired. After using the valve, our customer remarked that the design was a significant improvement over their previous sampling method both in the safety and purity of the sample. We were also recognized as “Best Technology Provider” at the Sulfur Products - Fuming Acid Safety Symposium for our work on this project. For any additional information about the design of this fume acid sampling valve project, contact us directly.