Reliably Detecting Carbon Monoxide
The best diaphragm pumps work reliably, effectively and unobtrusively in the background. But they must also often withstand extreme conditions. For example, in the early 1970s KNF designs a pump for use in carbon monoxide alarm systems. These systems monitor threshold limit values (TLVs) primarily in garages, tunnels and industrial furnaces. This limit value represents the amount of a substance – in this case carbon monoxide – that may be present in the air without posing any health risks, even in cases of repeated and long-term exposure, including workplace exposure for eight hours a day over a five day working week. In 1973, the limit value for carbon monoxide is 50 ppm (parts per million). Today, it lies at 28 ppm.
The task of the KNF pump is to draw the air to be tested in through an input filter and to convey it to a detection and alarm device. If a prescribed limit is measured, a visual and audible alarm is triggered and an air control system is activated. The development challenge lies in the fact that the pump has to operate continuously within a closed housing, generating as little heat as possible, while working against the high flow resistance of the piping between the inlet filter and the pump, which can be up to 150 meters long. In addition, KNF has to come up with a special design for an ambient air monitoring system for use in nuclear power plants.
KNF solves this technical challenge by initially mounting an unventilated motor with a reduced output in the housing of the standard 07 model. The flow rate is also reduced to 5 l/min. This is how the NK 640.7 E is developed – an extremely quiet and robust pump for continuous operation. KNF uses diaphragm compressors with a double diaphragm system for nuclear power plant applications. As the pumps are built to withstand temperatures of up to 50 degrees Celsius, KNF uses stainless steel for the heads and a special plastic for the diaphragm, valve plates and O-rings.
The pumps thus ensure a workplace air supply proven to be safe to breathe, in underground parking garages and nuclear power plants alike. And it goes without saying that these pumps run unobtrusively yet reliably, and do not require any maintenance.
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