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r <br /> 3 . Each pump shall be provided with a tandem double r <br /> mechanical seal running in an oil reservoir, composed of <br /> two separate lapped face seals , each consisting of one <br /> stationary and one rotating tungsten-carbide or silicon r <br /> carbide ring with each pair held in contact by a separate <br /> spring , so that the outside pressure assists spring <br /> compression in preventing the seal faces from opening . <br /> The compression spring shall be protected against r <br /> exposure to the pumped liquid . The pumped liquid shall <br /> be sealed from the oil reservoir by one face seal and <br /> sealed from the oil reservoir from the motor chamber by r <br /> the other. The seals shall require neither maintenance nor <br /> adjustment, and shall be easily replaced . Conventional <br /> double mechanical seals with a single spring between the r <br /> rotating faces , requiring constant differential pressure to <br /> effect sealing and subject to opening and penetration by <br /> pumping forces, shall not be considered equal to tandem .. <br /> seal specified and required . <br /> 4. A sliding guide bracket shall be an integral part of the _ <br /> pumping unit, and the pump casing shall have a machined <br /> connecting flange to connect with the cast iron discharge <br /> connection , which shall be bolted to the floor of the sump <br /> with stainless steel anchor bolts and so designed as to <br /> receive the pump connection without the need of any bolts <br /> or nuts. Sealing of the pumping units to the discharge <br /> connection shall be accomplished by a simple linear <br /> downward motion of the pump, with the entire weight of the <br /> pumping unit guided by 304 stainless steel guides which <br /> will press it tightly against the discharge connection . No r <br /> portion of the pump shall bear directly on the floor of the <br /> sump , and no rotary motion of the pump shall be required <br /> for sealing . .. <br /> 5 . Pump motors shall be housed in an air-filled , watertight <br /> casing . Motors shall be a NEMA Design B with a 1 . 15 r <br /> service factor. Insulation shall be moisture-resistant NEMA <br /> Class F with a maximum temperature rise of 90 degrees <br /> Celsius above ambient temperature (4 degrees Celsius ) . <br /> Motor characteristics are noted on the Drawings . Pump <br /> motors shall have cooling characteristics suitable to permit <br /> continuous operation , in a totally, partially or non- <br /> submerged condition . Each motor shall incorporate an <br /> ambient temperature compensated overheat sensing <br /> device and a moisture sending device wired in series . The <br /> protective devices shall be wired into the pump controls in r <br /> such a way that if either device operates, the pump will <br /> shut down . The devices shall be self-resetting . The cable <br /> shall be fixed to the pump using a watertight trumpet <br /> assembly. The pump shall be capable of running <br /> continuously in a totally dry condition under full load , <br /> r <br /> 8 - 5 <br /> r <br />