Vacuum Technology Book, Volume II

4.3.2 Application

Their hydrocarbon-free suction chambers make diaphragm pumps particularly well suited as dry backing pumps for turbomolecular pumps with a Holweck stage. Even two-stage diaphragm pumps that can reach an ultimate pressure of approximately 5 hPa. This is sufficient for backing of pumps for Holweck turbopumps. The clean vacuum is particularly useful for analytical and R&D applications. Diaphragm pumps, too, do not displace water vapor without gas ballast. Even the low volumes of water vapor that desorb from the walls of high vacuum equipment can allow the ultimate pressure of a diaphragm pump to increase dramatically. However, some diaphragm pumps are equipped with a gas ballast valve that operates in accordance with a patented process. For this purpose, gas is admitted into the connection channel between the first and second stages of two-stage diaphragm pumps, and this is connected with the suction chamber of the first stage via a small hole.

Diaphragm Pumps
Model Pumping speed Ultimate pressure Applications
MVP 003-2 0.25 m³ · h-1 ≤ 7.0 hPa Small turbopump pumping stations (ideal with HiPace 10 and HiPace 80), mobile analysis devices, MiniTest helium leak detector regeneration
MVP 006-4 0.25 m³ · h-1 ≤ 2.0 hPa Small turbopump pumping stations (ideal with HiPace 10 and HiPace 80), mobile analysis devices
MVP 015-2 0.5 m³ · h-1 ≤ 3.5 hPa Turbopump pumping stations, leak detectors, research laboratories, analytical and chemical applications
MVP 015-4 0.5 m³ · h-1 ≤ 0.5 hPa
MVP 030-3 1.8 m³ · h-1 ≤ 2.5 hPa
MVP 040-2 2.3 m³ · h-1 ≤ 4.0 hPa
MVP 070-3 3.8 m³ · h-1 ≤ 1.0 hPa
MVP 070-3 C 3.4 m³ · h-1 ≤ 1.5 hPa Corrosive gas applications requiring a hydrocarbon-free vacuum

Table 4.12: Diaphragm pump performance data

If greater volumes of moisture accumulate and diaphragm pumps without gas ballast are used, suitable separators or cooling traps must be connected upstream to prevent significant condensate formation in the pump. However, the ultimate pressure will nevertheless increase.