CORROSION.
Darling-Pelton Butterfly Valve, with continuous and adjustable rubber seating ring, which provides full 360° sealing.
Surer sealing...easier maintenance
wth DARLING-PELTON BUTTERFLY VALVES D a r l i n g - P e l t o n R u b b e r Seated Butterfly V a l v e s a r e d e s i g n e d t o give b u b b l e - t i g h t shut-off, easy o p e r a t i o n and trouble-free service t h r o u g h o u t the life of the valve. T h e sealing m e m b e r is a c o n t i n u o u s r e s i l i e n t r i n g displaced from the o p e r a t i n g s h a f t . . . and fully adjustable t o give b u b b l e - t i g h t closure around the circumference of the disc. T h e s e h i g h - p e r f o r m a n c e valves are designed in a c c o r d a n c e w i t h A . W . W . A . specifications...for hydrostatic o p e r a t i n g p r e s s u r e s u p t o 125 psi and velocities u p to 16 feet p e r s e c o n d . I n a d d i t i o n t o water service, they have been successfully used o n v a c u u m , gas and chemical service.
Close-up view of installation in large municipal water plant.
sludge formed on probe elements normally have much higher electrical resistances than the metal and hence do not interfere with probe measurements. In systems in which a nonnuiform type of corrosion is encountered, the electrical-resistance .probe has not been satisfactory. Although probe elements can be visually or metallographically examined to determine the presence of other forms of corrosion, such as pitting, intergranular corrosion, or nitriding, the smallness of the element would make questionable the accuracy of such information. Some difficulty has occurred in the operation of new probes. Problems associated with this purely mechanical-type failure have been eliminated by checking all new probes in the laboratory prior to their installation in a system. Also, a standard resistance bridge has been designed to check the probe meter periodically. From the experience gained thus far, it would appear that with proper application, the electricalresistance probe can be made a very useful tool in plant corrosion studies. T h e construction and the operating principle of the electricalresistance probe do, of course, limit its ability to detect or measure accurately all of the various types of corrosion. However, where the attack occurring in a system can be measured in the form of general corrosion by the proper selection of material for the probe element, the resistance probe should be a useful complement to weight-loss specimen testing. It should prove most valuable in correlating corrosion with changes in operations or in finding the reason for sudden corrosion failures. Another possible widespread use could be in the evaluation of corrosion-preventive measures such as inhibitors.
T o get all the facts, write us for Bulletin N o . 5904. View of Darling-Pelton Butterfly Valves installed in Pittsburgh's new filtration plant.
DARLING
DARLING VALVE & MANUFACTURING CO.
VALVES
Canada
W i l l i a m s p o r t 3 2 , Pa. Manufactured in Canada by Valve & Hydrant Co., Ltd., Brantford
Circle No. 1 on Readers' Service Card
74 A
INDUSTRIAL AND ENGINEERING CHEMISTRY
7,
Ontario
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