Smoke testing refers to various classes of tests of systems, usually intended to determine whether they are ready for more robust testing. The expression probably was first used in plumbing in referring to tests for the detection of cracks, leaks or breaks in closed systems of pipes. [1]
Pre-dating the term itself, smoke tests were performed to detect leaks in wooden sailing vessels at least as early as 1836. After making a slow fire in the bottom of the hold, Richard Henry Dana writes, "Wherever smoke was seen coming out we calked and pasted and, so far as we could, make the ship smoke tight." [2]
The plumbing industry started using the smoke test in 1875. [3]
In plumbing a smoke test forces non-toxic, artificially created smoke through waste and drain pipes under a slight pressure to find leaks. [4] Plumes of smoke form where there are defects. This test can be performed when the plumbing is brand new, but more often it is used to find sewer gas leaks that may plague a building or an area. [4] Any sign of smoke escaping can be considered a possible site for sewer gas to escape. Sewer gas typically has a rotten egg smell and can contain methane gas, which is explosive, or hydrogen sulfide gas, which is deadly.
Plumbing smoke tests are also used to find places where pipes will spill fluid, [4] and to check sanitary sewer systems for places where ground water and storm runoff can enter. Smoke testing is particularly useful in places such as ventilated sanitary sewer systems, where completely sealing the system is not practical.
When smoke testing a sanitary sewer system it is helpful to partially block off the section of sewer to be tested. This can be done by using a sand bag on the end of a rope. The sand bag is lowered into the manhole and swung into position to partially block lines. Completely blocking the line can cause water to back up and prevent smoke from escaping through defects. Smoke testing may not be done after rain or when ground water is unusually high as this may also prevent detection of defects.
Large downdraft fans, usually powered by gasoline engines, are placed on top of open manholes at either end of the section to be tested. If possible all lines in the manholes except for the line between the manholes are partially blocked. Smoke is created using either a smoke bomb or liquid smoke. Smoke bombs are lit and placed on a grate or in a holder on top of each fan, while liquid smoke is injected into the fan via a heating chamber. The fans create a pressure differential that forces the smoke into the sewer at a pressure just above atmospheric. With properly installed plumbing, the traps will prevent the smoke from entering the house and redirect it out the plumbing vents. Defective plumbing systems or dry traps will allow smoke to enter the inside of the house.
The area around the section being tested is searched for smoke plumes. Plumes coming from plumbing vents or the interface between the fan shroud and manhole rim are normal; however, smoke plumes outside of the manhole rim are not. Plumes are marked, usually with flags, and defects are noted using measurements from stationary landmarks like the corners of houses. The plumes or markers may also be photographed.
In woodwind instrument repair, a smoke test involved plugging one end of an instrument and blowing tobacco smoke from the tester's mouth into the other to test for leaks. Escaping smoke revealed improperly seated pads and faulty joints (i.e. leaks). After this test the instrument was cleaned to remove nicotine and other deposits left by the smoke. [5]
Described in a repair manual written in the 1930s,[ citation needed ] smoke testing is considered obsolete, [ citation needed ] and is no longer used by reputable technicians.[ citation needed ] The usual alternative to smoke is to place a bright light inside the instrument then check for light appearing around pads and joints.[ citation needed ]
In the same way that plumbing and woodwind instruments are tested, the vacuum systems of automobiles may be tested in order to locate difficult-to-find vacuum leaks. Artificial smoke is deliberately introduced into the system under slight pressure and any leaks are indicated by the escaping smoke. [6] Smoke can also be used to locate difficult-to-find leaks in the fuel evaporative emissions control (EVAP) system. [6]
In infectious disease control a smoke test is done to see whether a room is under negative pressure. A tube containing smoke is held near the bottom of the negative pressure room door, about two inches in front of the door. The smoke tube is held parallel to the door, and a small amount of smoke is then generated by gently squeezing the bulb. Care is taken to release the smoke from the tube slowly to ensure the velocity of the smoke from the tube does not overpower the air velocity. If the room is at negative pressure, the smoke will travel under the door and into the room. If the room is not at negative pressure, the smoke will be blown outward or will stay stationary.
Sewerage is the infrastructure that conveys sewage or surface runoff using sewers. It encompasses components such as receiving drains, manholes, pumping stations, storm overflows, and screening chambers of the combined sewer or sanitary sewer. Sewerage ends at the entry to a sewage treatment plant or at the point of discharge into the environment. It is the system of pipes, chambers, manholes, etc. that conveys the sewage or storm water.
A plumber is a tradesperson who specializes in installing and maintaining systems used for potable (drinking) water, and for sewage and drainage in plumbing systems.
A hydrostatic test is a way in which pressure vessels such as pipelines, plumbing, gas cylinders, boilers and fuel tanks can be tested for strength and leaks. The test involves filling the vessel or pipe system with a liquid, usually water, which may be dyed to aid in visual leak detection, and pressurization of the vessel to the specified test pressure. Pressure tightness can be tested by shutting off the supply valve and observing whether there is a pressure loss. The location of a leak can be visually identified more easily if the water contains a colorant. Strength is usually tested by measuring permanent deformation of the container.
A sanitary sewer is an underground pipe or tunnel system for transporting sewage from houses and commercial buildings to a sewage treatment plant or disposal. Sanitary sewers are a type of gravity sewer and are part of an overall system called a "sewage system" or sewerage. Sanitary sewers serving industrial areas may also carry industrial wastewater. In municipalities served by sanitary sewers, separate storm drains may convey surface runoff directly to surface waters. An advantage of sanitary sewer systems is that they avoid combined sewer overflows. Sanitary sewers are typically much smaller in diameter than combined sewers which also transport urban runoff. Backups of raw sewage can occur if excessive stormwater inflow or groundwater infiltration occurs due to leaking joints, defective pipes etc. in aging infrastructure.
A drain cleaner is a method of unblocking sewer pipes or clogged wastewater drains. The term may also refer to a mechanical device such as a plumber's snake, drain auger, toilet plunger, or similar device. Occasionally, the term is applied to a plumber or other individual who performs the drain cleaning and hygiene. Chemical drain cleaners can also be used.
In modern plumbing, a drain-waste-vent is a system that allows air to enter the plumbing system to maintain proper air pressure to enable the removal of sewage and greywater from a dwelling. Drain refers to water produced at fixtures such as sinks, and showers; waste refers to water from toilets. As the water runs down, proper venting is required to allow water to flow freely, and avoid a vacuum from being created. As the water runs down air must be allowed into the waste pipe either through a roof vent (external), or an internal vent.
Ultra-high vacuum (UHV) is the vacuum regime characterised by pressures lower than about 100 nanopascals. UHV conditions are created by pumping the gas out of a UHV chamber. At these low pressures the mean free path of a gas molecule is greater than approximately 40 km, so the gas is in free molecular flow, and gas molecules will collide with the chamber walls many times before colliding with each other. Almost all molecular interactions therefore take place on various surfaces in the chamber.
In pipeline transportation, pigging is the practice of using pipeline inspection gauges or gadgets, devices generally referred to as pigs or scrapers, to perform various maintenance operations. This is done without stopping the flow of the product in the pipeline.
Sewer gas is a complex, generally obnoxious smelling mixture of toxic and nontoxic gases produced and collected in sewage systems by the decomposition of organic household or industrial wastes, typical components of sewage.
A helium mass spectrometer is an instrument commonly used to detect and locate small leaks. It was initially developed in the Manhattan Project during World War II to find extremely small leaks in the gas diffusion process of uranium enrichment plants. It typically uses a vacuum chamber in which a sealed container filled with helium is placed. Helium leaks out of the container, and the rate of the leak is detected by a mass spectrometer.
Pipeline video inspection is a form of telepresence used to visually inspect the interiors of pipelines, plumbing systems, and storm drains. A common application is for a plumber to determine the condition of small diameter sewer lines and household connection drain pipes.
A leak is a way for fluid to escape a container or fluid-containing system, such as a tank or a ship's hull, through which the contents of the container can escape or outside matter can enter the container. Leaks are usually unintended and therefore undesired. The word leak usually refers to a gradual loss; a sudden loss is usually called a spill.
A flue is a duct, pipe, or opening in a chimney for conveying exhaust gases from a fireplace, furnace, water heater, boiler, or generator to the outdoors. Historically the term flue meant the chimney itself. In the United States, they are also known as vents for boilers and as breeching for water heaters and modern furnaces. They usually operate by buoyancy, also known as the stack effect, or the combustion products may be 'induced' via a blower. As combustion products contain carbon monoxide and other dangerous compounds, proper 'draft', and admission of replacement air is imperative. Building codes, and other standards, regulate their materials, design, and installation.
A series of ten explosions took place on April 22, 1992, in the downtown district of Analco Colonia Atlas in Guadalajara city, Jalisco state, Mexico. Numerous gasoline explosions in the sewer system and fires over four hours destroyed 8 kilometres (5.0 mi) of streets. Gante Street was the most damaged. By the accounting of Lloyd's of London, the reported number of people killed was about 252, although many estimate that the catastrophe actually caused at least 1,000 deaths. About 500 to 600 people were missing, nearly 500 were injured and 15,000 were left homeless. The estimated monetary damage ranges between $300 million and $3 billion. The affected areas can be recognized by the more modern architecture in the areas that were destroyed.
A fitting or adapter is used in pipe systems to connect straight sections of pipe or tube, adapt to different sizes or shapes, and for other purposes such as regulating fluid flow. These fittings are used in plumbing to manipulate the conveyance of water, gas, or liquid waste in domestic or commercial environments, within a system of pipes or tubes.
In plumbing, a trap is a U-shaped portion of pipe designed to trap liquid or gas to prevent unwanted flow; most notably sewer gases from entering buildings while allowing waste materials to pass through. In oil refineries, traps are used to prevent hydrocarbons and other dangerous gases and chemical fumes from escaping through drains. In heating systems, the same feature is used to prevent thermo-siphoning which would allow heat to escape to locations where it is not wanted. Similarly, some pressure gauges are connected to systems using U bends to maintain a local gas while the system uses liquid. For decorative effect, they can be disguised as complete loops of pipe, creating more than one U for added efficacy.
A vacuum sewer or pneumatic sewer system is a method of transporting sewage from its source to a sewage treatment plant. It maintains a partial vacuum, with an air pressure below atmospheric pressure inside the pipe network and vacuum station collection vessel. Valves open and reseal automatically when the system is used, so differential pressure can be maintained without expending much energy pumping. A single central vacuum station can collect the wastewater of several thousand individual homes, depending on terrain and the local situation.
Infiltration/Inflow (I/I) causes dilution in sanitary sewers. Dilution of sewage decreases the efficiency of treatment, and may cause sewage volumes to exceed design capacity. Although inflow is technically different from infiltration, it may be difficult to determine which is causing dilution problems in inaccessible sewers. The United States Environmental Protection Agency defines the term infiltration/inflow as combined contributions from both.
Copper tubing is most often used for heating systems and as a refrigerant line in HVAC systems. Copper tubing is slowly being replaced by PEX tubing in hot and cold water applications. There are two basic types of copper tubing, soft copper and rigid copper. Copper tubing is joined using flare connection, compression connection, pressed connection, or solder. Copper offers a high level of corrosion resistance but is becoming very costly.
A pipe plug is a tool or material for the temporary sealing of pipelines in sewerage and other liquid and gas transportation systems; typically for maintenance or non-pressurized line testing. A pipe plug is also known as an inflatable plug, mechanical pipe plug, pipe test plug, pipeline isolation plug, expandable plug, pipe bung, pipe stopper, pipe packer, pneumatic pipe plug or pipe balloon depending on the region where it is used.