HEED filter

Fig. iL Pulse sequences for pseudo triple-resonance experiments with passive selection of satellites (a) z-filtered 2D-"X, H( "Y) INEPT. (b) -BIRD H,"X( "Y) HMQC. (c) H,"X( "Y) HMQC experiment with biselective excitation pulse (bis) biselective excitation may be achieved with DANTE or P-BIRD sequences, binomial pulses, or shaped pulses. (d) H, X( "Y) HEED-INEPT." ... 

The cartridge filter is typically a 5- to 10-micron nominal cutoff filter. The housing can be PVC, FRP, or SS (again, take heed of the materials of compatibility). It should be equipped with a differential pressure gauge to measure the pressure drop across the filter. Cartridge filters should be changed out with every new cleaning solution. 

---