After the drenching
February 8, 2009
One of the key components to proper equipment selection is the responsibility of the owner/employer to know the hazards in his workplace. Not only does this knowledge apply to determining what type of emergency drench device is best suited for the hazard, but, in many cases, the end user must know how to properly and legally dispose of the contaminated flushing fluid after it is used to irrigate the exposed worker. Depending on the hazardous substance involved, local, state and/or federal statutes may affect the disposal of this waste.
An open gravity drain to the sewer system has long been used to dispose of contaminated fluids from a shower or eyewash. In locations where no drain was available, the waste fluid was simply mopped up and thrown out. But as more regulations govern the retention and disposal of contaminated flushing fluid, finding alternatives has become necessary.
One of the most effective methods is a vacuum and waste drainage system. This system will capture and contain the contaminated flushing fluid with no possible exposure or leakage into the public water system.
Vacuum drainage systems also offer the opportunity to create a cleaner, safer environment and reduce health hazards associated with the disposal of hazardous waste by depositing the contaminated fluid into a containment vessel for controlled disposal.
Vacuum drainage systems
Vacuum drainage systems are a viable alternative to gravity drainage that uses the combined forces of atmospheric and vacuum pressures to move the contaminated flushing fluid from the shower or eyewash to sanitary waste lines or containment vessels without requiring floor drains or underground piping.
A vacuum drainage system is an engineered plumbing system consisting of three basic components:
- A vacuum generating and temporary waste collection center (Vac Center);
- A vacuum drainage piping network;
- Vacuum valve and control components used to isolate the vacuum piping network from atmospheric pressure and collect waste at its point of origin.
A Vac Center consists of waste collection tanks, vacuum pumps and system controls which automate the operation of the system. The size of the system’s waste collection tanks and vacuum pump capacities are based on the gallons per minute specifications of the specific shower or eyewash units that are attached to the system. It is also important to note that sizing of both tanks and pumps is always based on providing the Vac Center full redundancy in system capacity.
The piping network consists of the connection to a collection point at the individual shower or eyewash fixture, as well as the vertical and horizontal piping needed to transport the waste from the point of use to the vacuum collection center. It is important that the internal surfaces of the piping are smooth and nonporous. For this reason, the piping network is typically specified with PVC, copper or stainless pipe with approved DWV waste fittings, allowing for smooth transition of waste through the piping network.
The vacuum pressure in the piping network is separated from atmospheric pressure at the waste collection vessel serving the emergency fixture by means of vacuum valve and control components. This third group of components also includes an intermediate waste collection vessel, known as an Accumulator; a normally closed interface valve, known as the Extraction Valve, which separates atmospheric pressure at the Accumulator from vacuum pressure in the piping network; and a Controller which operates the Extraction Valve.
Contaminated flushing fluid from the emergency drench equipment drains into the Accumulator. As the Accumulator fills, atmospheric pressure between the Accumulator and Controller becomes sealed off. This pressure causes the Controller to open the normally closed Extraction Valve, allowing atmospheric pressure to enter through the Accumulator, aerate the collected waste and move it from the Accumulator into the waste piping network. The Extraction Valve remains open until contaminated flushing fluid is cleared from the Accumulator and is sent to the Vac Center.
Once the waste fluid has reached the Vac Center, it is temporarily held before being automatically discharged to either a containment vessel or, if possible, a municipal sewer connection, thus allowing for controlled waste disposal.
Vacuum systems allow drainage to be provided anywhere within the facility without requiring floor drains or vent stacks. Emergency drench equipment can be placed where necessary without concern for wastewater cleanup or damage associated with equipment use or testing.
The waste piping network’s flexibility to run vertically as well as horizontally, through smaller space limited areas and without requirement to plan around obstructions, offers more choices to plant owners. This is especially beneficial in facilities where relocation of emergency equipment is required due to manufacturing concerns requiring regular change in layout.
Because air can leak in but waste cannot leak out, ex-filtration of hazardous waste effluent into the environment is also eliminated with a vacuum drainage system.