Figure 7From: Surface properties of glass micropipettes and their effect on biological studies The effect of pressure on tip diameter and average surface roughness. This control sets the pressure generated by the air compressor during the active cooling phase of the pull cycle. The unit of pressure is psi. Changes of less than 10 units will not be noticeable. Pressure is another way of controlling tip length and does not change the size of pipette tip significantly.Back to article page