Diaphragm Pump Heads

If aggressive or toxic materials have to be conveyed, hermetically sealed constructions are necessary. Diaphragm pumps meet this requirement because the never absolutely leakproof piston seal (dynamic or grinding seals are never absolutely leakproof) has been replaced by the diaphragm s static seals at the diaphragm clamp. 

---

Fig. 4.1-8. Types of reciprocating metering pumps P, Plunger pump head DH, Diaphragm pump head (hydraulic)...

Magnetic linear drives (Fig. 4.1-8e) are distinguished by their ease of operation and their small size. They are suitable for flow rates <10 1/h and pressures up to 500 bar with diaphragm pump heads (Fig. 4.1-9). 

A), Drive system with straight thrust crank for multi-head arrangement B), Diaphragm pump head for the pressure range up to 500 bar. 

Pump. Solution is pumped at low flow rate through the cell by means of a Lapp Pulsafeeder pump Model LS-10. Difficulty in maintaining constant flow at slow flow rates was traced to small air pockets in the diaphragm pump head that would not spontaneously pass the exit check valve. This difficulty was remedied by the aspiration of the feed solution to remove dissolved gases. To minimize the hazard of implosion of the feed reservoir, a cage was made from 1/4-inch hardware cloth to fit the 20-liter reservoir. 

Figure 1 Process Diaphragm Pump Head with PTFE Diaphragm...

Figure 9.20 Diaphragm pump head with hydraulically actuated position-controlled PTFE-...

Figure 9.24 Diaphragm pump head with metal diaphragm and hydraulically actuated...

Figure 13.14 Diaphragm pump heads (a) with PTFE diaphragm for 40 MPa (b) with metal diaphragm for 100 MPa. 1 Diaphragms 4 replenishingvalve 5 pressure relief valve 7 oil reservoir source LEWA Company, Germany).

The diaphragm is the central element which determines the whole pump head design and its size. PTFE diaphragms are predominantly used - for higher pressures metal diaphragms, and for special designs elastomeric diaphragms (Table 2). 

Fig. 4.6.5. Schematic representation of reciprocating pump. 1. motor driven piston (stroke height can be changed) 2, O-ring piston seal 3, diaphragm 4, pump head with back valves 5. eluent inlet 6. eluent outlet.

Drive mechanism and pump head piston reciprocating pump or diaphragm reciprocating pump 23... 

Fig. 8. Gradient system using a dual-head sinusoidal-drive counter-piston diaphragm reciprocating pump, a, a = containers of solvents A and B, b, b, = pump heads, c = pump motor, d, d = variable-speed or stepping motor to adjust the course of the counter-piston, e, e = pulse damping systems and flow-rate sensors, f = mixing chamber, g = to column, h = programmer.

---