Spacer volume

The volume of Class G cement is the sum of the spacer volume, annular volume in the cased portion of the borehole and the applicable annular volume in the open-hole section of the borehole. The annular capacity of the cased portion of the borehole is... 

A mathematical model incorporating impaction, aerosol half-life, spacer volume, dead space, and leakage was recently developed and validated (25). This model correctly predicted the aerosol deUvery from common spacers. 

This interaction between spacer volume and pMDI vapor pressure can cause a twofold change in the fine-particle output from different pMDI and spacer combinations (14). 

Drug output increases with spacer volume. 

The ratio of fine to coarse particles is dependent on spacer volume, spacer shape, and pMDI vapor pressure. 

Figure 5 The effect of spacer volume on dose delivery. The aerosol from a budesonide pMDI was analyzed by the Anderson impactor (U.S. throat) 2 s after actuation (28 L/min) through Nebuhaler and Babyhaler, both of which had been primed to prevent electrostatic effects. Both spacers are of similar length but have different diameters (80 versus 50 mm). The aerosol was airborne for a longer time in the spacer with the larger diameter correspondingly, the total dose was larger, mainly due to an increased coarse particle dose.

The drug output increases with spacer volume, while the ratio between line and coarse particles is dependent on the balance between spacer volume and pMDI vapor pressure. Electrostatic charges in plastic spacers cause a clinically significant reduction of lung dose thus, nonelectrostatic devices should be used in the future. Drug delivery is reduced by the proportion dead space to tidal volume. Differences in spacer construction may change drug delivery several-fold. Therefore each pMDI-spacer combination should be considered a separate entity and the use of a universal spacer for different pMDIs should be avoided. 

Thus the volume of Class G cement slurry to be used to cement the well (excluding spacer, but considering the excess factor) is... 

R. C. Navarrete, J. M. Seheult, and M. D. Coffey. New biopolymers for drilling, drill-in, completions, spacer, and coil-tubing fluids Pt 2. In Proceedings Volume. SPE Oilfield Chem Int Symp (Houston, TX, 2/13-2/16), 2001. 

Figure 2. Left Family of softball" monomers 4-7. Different spacers between the centerpiece and the glycoluril binding sites permit assembly of dimers with cavity volumes between 186 A3 and 313 A3. Right Computer-minimized...

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