The Exhaust Primer is an air ejector adapted to an engine-driven pump. An adapter is attached to the exhaust stack to which the ejector is attached, and a lever-operated "exhaust valve" is provided by which the engine exhaust gases are momentarily diverted through the ejector during the priming period. "Momentarily" means 10 seconds to 2 minutes depending on the suction lift and length and size of the suction line. It operates on low engine exhaust pressure. When the exhaust valve is closed, the gases are directed through the ejector nozzle and air is drawn from the pump through the ejector suction.

Exhaust primers have long been a preferred means of priming engine-drive centrifugal pumps because they are semi-automatic, efficient, easy to install, and economical. Since there are no moving parts, they will last indefinitely.

Under ideal conditions, at sea level, suction lifts of 25 ft may be obtained. For average conditions suction lifts up to 20 ft may be expected.

All standard Protek Exhaust Primers are designed to operate at 12 to 14 lb pressure and thereby provide maximum lift and rapid priming. The back-pressure created in the short time required for priming is not excessive for four-cycle (four stroke) engines. Note that exhaust primers generally will not work effectively on single cylinder engines because of the pulsating pressure effect. Nor will they work well on two-cycle (two stroke) engines because this type engine does not produce enough back pressure for the ejector to function properly.

Since the volume of the exhaust air discharged from an engine is dependent on its piston desplacement and speed it is most important that the proper size ejector be used in each application so that the necessary pressure will be created in the ejector at the desired engine speed. If less than minimum pressure is provided the primer will not develop its maximum vacuum. On the other hand, if the speed is too great, unnecessary back-pressure is created on the engine.

Normal speeds for small engines are usually higher that for large engines, therfore primers may be generally classified in two groups as follows:

To insure proper use of an exhaust primer, the operator should have a way of determining the correct speed to run the engine during the priming period. Installing a tachometer on the engine to determine the exact speed at which the primer operates best can do this.

A more practical and economical method is to install a pressure gauge permanently at the engine exhaust and instruct the operator to run the engine at the speed required, producing the proper pressure at the primer. This gauge permits periodic checks. After the engine has been in use two or three seasons it might not develop as much pressure at the same speed as when it was new.

After the ejector has been installed on the engine a vacuum gauge should be temporarily connected to the ejector suction, preferably through a short length of hose, and the engine speed increased gradually, with the primer exhaust valve closed, until the gauge show a vacuum of 20" or more. This is the proper speed for priming. If a pressure gauge has been permanently installed on the engine exhaust as suggested above the pressure required for priming may be marked on the face of the gauge as a permanent guide to the operator.

If the pump is direct-coupled to the engine then priming connection MUST be made on the suction side of the pump. The connection should be at the highest point to insure the primer drawing the maximum amountof water into the pump case before water drawn into the primer. If the pump is the double suction type, the connection may be made into the case at both sides of the impeller.

Pumps that are connected to the engine through a clutch may be primed from the discharge side provided the clutch is disengaged while priming.

Air leaks are always a major problem in pump hook-ups and are more prevalent in portable pumping units than any other. They are, therefore the major source of trouble in priming a pump. Air leaks may cause excessive priming time or make priming impossible. Leaks may appear in the suction connections, the discharge valve or the shaft packing.

Protek primers are made of bronze and will last many seasons of normal use. About the only thing that will affect their operation would be an accumulation of trash, dirt or soot from the engine exhaust.

From the foregoing it is obvious that the exhaust primer is a simple accessory that will cause the user little or no trouble if correctly applied.

It is impossible for us as a manufacturer to foresee all of the circumstances under which our product may be used and, therfore, extremely difficult to provide an instruction manual to cover all quiestions that might arise. Consequently, this information is set forth in general terms for the benefit of distributors who should apply it to their own specific applications. Distributors are encouraged to provide appropriate instructions to their customers.