Rotary Evaporator Repair The well-known Biichi rotary evaporator, e.g., Ratavapora R or RE, is commonly used in many laboratories for solvent removal. After the evaporator has been used for a time, deterioration of the seal leads to air leakage and poor vacuum, necessitating the replacement of the original seal. Although the cost of the replacement is moderate (- $4-$11 in mid-1980 for Vitan", Game rubber or silicone vacuum gaskets), removal of the old seal ordinarily requires a rather costly special tool, $85. A newer style fluorocarbon seal is available which does not require any special tools for insertion or removal and is recommended for replacement use. However, substituting this new seal still entails the removal of the defective one. This is a difficult task without the special tool, since the press-fit of the standard seal is kxceptionally tight. Excessive force in removal must clearly be avoided if damage to the entire glass condenser assembly is to he prevented. In the absence of the special tool, we have recently used two different methods for removal of a defective seal. Both methods begin with the cutting away of the loose old rubber with a scalpel or X-act
