Potentially flammable and hazardous chemicals such as acetone and isopropyl alcohol are often stored in 55-gallon or larger drums for dispensing into smaller containers or at the point of use. Environmental, health, and safety directors often must identify the best type of pump to transfer these liquids as the wrong type of pump, or worse, employees tipping and pouring out contents, can be catastrophic. Accidental release of toxic or highly flammable materials can cause worker injuries, fires, and explosions.
Hazardous chemicals must include safety data sheets (SDS) and globally harmonized system (GHS)-compliant labels. The United Nations established GHS to create a worldwide, unified system to identify and communicate information about hazardous chemicals.
The SDS details potential environmental hazards, what to do in the event of small and large spills, and suggestions for treating injuries related to inhaling or coming into physical contact with chemicals. The SDS also identify required personal protective equipment (PPE) and safe storage guidelines.
Depending on the chemical substance, SDS can include descriptions of severe injuries, transgenic damage to cells and organs, and the possibility of death. For example, the SDS for the widely used solvent acetone mentions its extreme flammability and how it “burns with yellow bright flames… Vapors can flow along surfaces to distant ignition sources and flash back… even minimal static discharge can ignite acetone vapors.”
With such dire consequences in mind, proper storage and handling are outlined to prevent dangerous situations. For flammable and combustible liquids, that advice is consistent across most SDS and states:
- Avoid breathing fumes or vapors
- Keep away from heat, sparks, open flames, or hot surfaces (to avoid ignition)
- Keep containers tightly closed
- Bring in grounding or bonding devices for the container, receiving equipment
- Use explosion-proof electrical, ventilating, or lighting equipment (to avoid ignition)
- Take precautionary measures against static discharge (to avoid ignition)
Most states and municipalities have further adopted NFPA 30 Flammable and Combustible Liquids Code and OSHA 29 CFR 1910.106, fire codes addressing flammable liquid equipment, handling, storage, and use.
Ensuring safe delivery of chemicals requires proper safety training, use of PPE, and in some cases, further engineering controls.
Although SDS don’t state it directly, most – if not all – requirements spell out the need for a specialty pump to transfer flammable or combustible chemicals to smaller containers or at the point of use to maintain workplace safety.
Transfer equipment requirements
Whether mandatory or guideline, ensuring safe chemical transfer requires a sealed or closed-loop pump system that keeps vapors from escaping the container and prevents personnel contact. Systems must be designed using materials and seals that can withstand extended contact with the chemical and must include grounding wires to prevent static discharge. A sealed pump dispensing system enhances safety by eliminating spills, enabling environmentally safe transfer.
Eliminate ignition sources
A flame, hot surface, static electricity, or a spark generated by electricity or mechanical work can ignite combustible and flammable liquids, so it’s critical to eliminate external ignition sources when handling them. Highly volatile solvents are more hazardous because any vapor – volatile organic compounds (VOCs) – released can reach ignition sources several feet away and flash back to the liquid.
In transferring flammable liquids from large containers (>10L) to smaller ones, the flow of the liquid can create static electricity that could result in a spark. Static electricity build-up is possible whether using a pump or pouring the liquid. If the bulk container and receiving vessel are both metal, it’s important to bond the two by firmly attaching a metal bonding strap or wire to both containers and to the ground, which can safely dissipate the static charge.
Containers used to transfer Class 1 liquid (flammable with a flash point lower than 100°F) and Class 2 and 3 (combustible with a flashpoint higher than 100°F) must be grounded or bonded to prevent electrostatic discharge that could act as an ignition source. NFPA 30 Section 18.104.22.168 also requires a means to prevent static electricity during transfer/dispensing operations.
Chemical compatibility databases and guidance make selecting the correct pump for each chemical or formulation in aerospace manufacturing straightforward while maintaining workplace safety.
The correct pump for each application is often determined by the materials that will contact the chemicals. Each chemical has specific characteristics, so selecting the appropriate gasket, housing, and hose is critical for safety and equipment longevity. In addition, flammable liquids require a groundable pump. Established pump manufacturers compile detailed chemical compatibility databases that document the type of pump, gasket, hose, and whether the chemical needs to be groundable.
If the chemical is in the database, the pump often comes with a one-year warranty as it has been tested or the chemical manufacturer verified compatibility. When a chemical isn’t on the list, the pump manufacturer will review the SDS and, if necessary, conduct tests to determine the right pump.
Chemical compatibility testing
Testing can be as simple as soaking the standard gaskets in the chemical for 5 to 7 days. Because vapors are volatile, they are frequently more harmful than the liquid itself. When appropriate, vapor tests are conducted in which the elastomer gasket options (Viton, EPDM, Nitrile, and Santoprene) are suspended over the liquid. Pumps are then built, tested with each elastomer, and if none of these gaskets work for the application, designers can select Teflon or Kalrez gaskets.
With some complex aromatics, aliphatics, and flammable liquids, the plastic pump housing may also need to be tested. This test is a 60-day soak in the chemicals to see if the parts swell or bind with each other, which will cause the pump to fail.
By following the NFPA, OSHA, and other regulatory bodies’ recommendations, personnel can avoid hazards outlined in the SDS that could lead to physical injuries, chronic respiratory ailments, and even death.
Fortunately, protecting workers from harm can be relatively straightforward with proper safety training, the use of PPE, and applying engineering controls to prevent dangerous spills and chemical accidents.