The performance of Venturis in pulse jet filters has been shown to be important in the development of stable, low pressure drop filter operation. The Venturi can be regarded as a pump, with pump or fan like characteristics, and similar selection criteria can be applied to selection as those normally used for fans. The major difference between a fan and a Venturi used for this type of application is the requirement for low reverse pressure drop. The following conclusions have been made: different Venturis have different characteristics due to their varying shapes; increasing the pulse pressure increases the Venturi performance; larger Venturis give less pressure but more flowrate than smaller ones, for a given pulse tube geometry; and some Venturis are less resistant to filtration flow than others, and may be selected for that reason. The performance of fabric filters is heavily dependent upon good cleaning, and this in turn is dependent upon good Venturi design. The use of poor Venturis can be ameliorated by cleaning only at suitable pressure drop, and this can best be achieved using pressure initiated cleaning cycles, rather than simple timer controlled cycles., The performance of Venturis in pulse jet filters has been shown to be important in the development of stable, low pressure drop filter operation. The Venturi can be regarded as a pump, with pump or fan like characteristics, and similar selection criteria can be applied to selection as those normally used for fans. The major difference between a fan and a Venturi used for this type of application is the requirement for low reverse pressure drop. The following conclusions have been made: different Venturis have different characteristics due to their varying shapes; increasing the pulse pressure increases the Venturi performance; larger Venturis give less pressure but more flowrate than smaller ones, for a given pulse tube geometry; and some Venturis are less resistant to filtration flow than others, and may be selected for that reason. The performance of fabric filters is heavily dependent upon good cleaning, and this in turn is dependent upon good Venturi design. The use of poor Venturis can be ameliorated by cleaning only at suitable pressure drop, and this can best be achieved using pressure initiated cleaning cycles, rather than simple timer controlled cycles.