Floating restrictor

Fig. 25. Spectral-segmented spectrum of a glow discharge [58]. Grimm-type glow discharge lamp with floating restrictor (8 mm diameter) 50 mA, 3.5 torr, 2 kV [42] Plasmaarray spectrometer (LECO) steel sample 217 A (Research Institute, CKD, Prague, Czech Republic).

Fig. 72. Restrictor tube configurations and current-voltage characteristics of flat cathode dc glow discharges. (A) According to Grimm (B) floating restrictor (C) restrictor made of...

A modified version of the Grimm-type GDL has been described by Shao and Horlich [594], The source has a floating restrictor and is designed so as to replace an ICP torch in an ICP-MS. Therefore, the anode is slightly positive with respect to the earthed skimmer interface of the MS system. The simultaneous analysis of an unknown sample and a reference material was carried out by means of a system based on two pulsed GD sources housed within the same tube [595], Optimization of the relative position of the two cathodes was achieved by evaluating the signals produced in GD-MS when using the same specimen for each of them. 

Simple flow controllers use the differential pressure at an adjustable restrictor the plus and minus sides are on the two sides of a spring-supported diaphragm. These controllers are used as backflow (check) valves or as isolation valves, which shut off if the flow is reversed or too high. Level controllers with floats are in condensate separators often coupled with simple temperature controllers as in Figure 12.28. These devices contain an electrical jump switch and operate therefore as two-point On-Off controllers. Controllers without auxiliary energy are used, where it is not essential to have high control accuracy and when one must do without the auxiliary power for safety reasons. 

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