The chemically-resistant series N 840 and N 840.3 diaphragm pumps are single- and double-head, dry-running devices used in a wide range of laboratory applications. They transfer and pump down without contamination. The heart of these very compact pumps is a KNF structured diaphragm. This patented diaphragm was stress-optimized using the Finite Elements method. As a result, we were able to make the pumps smaller while increasing the service life of the diaphragm. Technical features: 100% oil-free transfer. Pure transferring and evacuation of gases. Highly compatible with vapors and condensation. Chemically-resistant. Suitable for highly aggressive or corrosive gases and vapors. Maintenance-free Environmentally friendly. Gastight, leakage rate approx. 6 x 10-3 mbar x L/s, not tested in serial production.