ACHEMA: New Gas Sampling Pumps for Emission Measurement Technology

Robust, easy to service and efficient

KNF pumps for stationary gas analyzer systems

Robust, easy to service and efficient – key qualities that manufacturers of stationary analyzer systems require from pump technology. KNF, a technology leader in the field of diaphragm pumps, will show three new pumps at ACHEMA 2018 in Frankfurt. Together, the N 922 and N 816 models and the optimized N 838 capture a wide range of applications in continuous emissions measurement.


ACHEMA is the world forum and leading show for the process industries. At booth E85 in hall 11.1, KNF will showcase new gas sampling pumps for integration into analytical instruments such as analyzer cabinets.


Manufacturers and users of measurement systems for stationary continuous emissions monitoring (CEM) have very specific requirements. These are governed by the properties of the process gas, site of operation and environmental conditions. A range of structural elements make KNF’s diaphragm gas pumps ideally suited to supplying precise measurement results on a permanent basis.

Durable: diaphragm gas pump N 816

KNF designed the N 816 in response to market demand for durability and robustness. Even over the long term, the N 816 stands up to humidity and condensation. The pump head components that come into contact with the medium are made from the chemically resistant materials PPS, EPDM, PTFE or FFPM.


The key technical characteristics include a flow rate of up to 16 l/min and an ultimate vacuum of 100 mbar abs. The pump’s small size facilitates integration within analyzer cabinets and thus supports space-saving solutions. Two brushless DC motor options are available, including one motor developed in-house by KNF, allowing systems to be tailored to specific customer needs.

Easy to service: diaphragm gas pump N 922

Owing to the long service life of stationary emission measurement systems, the ease of servicing built-in components is an important feature. The N 922 fulfills this need in every regard. The only parts which have to be replaced are the diaphragm and valves. This task must be performed once a year depending on how the pump is used. Maintenance work can be easily carried out even on assembled analytical systems using standard tools. Thanks to its robust design, there is no need to remove the pump for servicing, thus ensuring that the measurement technology remains ready for operation even under extreme conditions. Few replacement parts, long periods between required maintenance work and low costs for spare parts all add up to pleasingly low operating costs.


The N 922 gas sampling pump is chemically resistant, making it suitable for use with very aggressive gases. Since it is intended for use in gas analyzer systems, the diaphragm pump has been designed to be especially durable. Compared with the previous model (N 726 FTE), the more technologically advanced N 922 can operate at higher ambient temperatures of up to 60oC.


The pump has a flow rate of 16 l/min, which can be optionally adjusted using a bypass valve. It achieves an ultimate vacuum of at least 200 mbar abs and has an operating pressure of 2 bar.


An ATEX version of the pump is also available. Both the pump head and the motor conform to ATEX and IECEx standards (pump unit: Ex II 2G c IIB + H2 T3 X, motor: Ex II 2G Ex de IIC T4), and can be used in ambient temperatures of up to 50°C.


The compressor housing in both models can be moved in increments of 90 degrees separately from the motor in order to be positioned as required for condensate discharge.

Efficient: the optimized N 838

N 838 series gas pumps are used in numerous analytical instruments. The success of the product line can be attributed to the flow rate of up to 60 l/min and the ultimate vacuum of up to 90 mbar abs in an extremely compact design.


KNF has reworked how the components involved in gas conduction interact and has also optimized the valve construction, which consists of valve plates and sealing rings. In addition, the connecting system for the pump heads in the multistage pump version has been redesigned. All in all, the improvements serve to ensure a more efficient gas flow through the pump head.


A selection of single- and double-headed series models with AC, DC and DCB motors are available in the product range.