Product Overview | Air/Oil Ratiotrols
Table 2
7052 Ratiotrols proportion oil flow to combustion air flow in cross-connected control systems. Outlet oil pressure from the Ratiotrol is proportional to the impulse air signal, see Table 2. Therefore, as combustion air is turned up or down, the Ratiotrol causes oil to follow it in proportion. Desired air/oil ratio is set with a manual valve (see 1813 Sensitrol™ Oil Valve bulletin) at the burner.
Pressure Multiplication Factor
Size
Low flow Maximum flow
7052-01 7052-0
9:1
7:1
14:1
10.5:1
Spring Bias: 7052-01:+1.9/–1.5 psi 7052-0: +3.2/–2.5 psi
MULTIPLE BURNERS
Table 3
CAPACITIES gph (#2 oil) air impulse pressure, "w.c. 13.9 20.8 27.7 41.6
A single Ratiotrol can serve several burners when it is cross-connected downstream of the zone air control valve if burners are on one side of furnace and difference in their elevation is less than 12". PISTON ACCUMULATORS If Ratiotrol is in light oil line between valves that are closed when burners are shut off, radiant heat from furnace could expand oil trapped in the line, bursting Ratiotrol diaphragms and damaging gauges. Install one or more 8521-01 Accumulators downstream of Ratiotrol to prevent this. See Bulletin 8521-01.
Ratiotrol 7052-01
55 36 161 101
67 45
78 52
95 63
7052-01-V 7052-0 7052-0-V
197 123
227 142
274
171
FLOW and PRESSURE
Flow and pressure are determined using the table in this bulletin.
Example: Given a 7052-01 with 25 psig inlet pressure and 16"w.c. impulse air at high fire, what is the maximum outlet pressure and maximum flow at high fire.
SPECIFICATIONS Operating inlet pressure: 25-30 psi Emergency inlet pressure: 50 psi Maximum oil temperature: 180°F for standard 7052
With 25 psig inlet and 16"w.c., based on Table 1 the conditions are suitable to provide the maximum possible flow.
From Table 2 we can deteremine the maximum oil outlet pres- sure. With 16"w.c. impulse pressure oil outlet pressure is 16 x 7 = 112"w.c. or 4.04 psig.
300°F for 7052- -V (with Viton diaphragms)
Oil grades:
7052-01: light oils only 7052-0: #1 through #6 oils Optional gauges (and thermometer): 7052-01-WG: inlet and outlet oil pressure gauges with gauge cocks, air impulse pressure gauge 7052-0-WTG: inlet and outlet oil pressure gauges with gauge cocks, air impulse pressure gauge, dial thermometer
By using linear interpolation on Table 3, an air impulse pressure of 16"w.c. give 58.65 gph.
TURNDOWN
Turndown is determined based on using the Square Root Law of air impulse pressure to oil flow. The more impulse air available the higher the flow turndown that can be achieved. As a general rule the minimum impulse air pressure should not be less than 1"w.c. for good control.
Table 1
Recommended Inlet Pressures
Size
Air impulse Inlet pressure ('w.c.) (psig)
Example: Given the example above, what would be the flow turndown?
7052-01
10-55
25 30 35 25 30 35 45
High fire impulse pressure is 16"w.c. A minimum impulse pressure of 1" water column at low fire means the 16:1 air impulse would be .
62 69
16
1 √
7052-0
10-28
35 42 59
Which gives 4:1 turndown from the max flow of 58.65 gph, which is approximately 14.66 gph.
Bulletin 7052 Page 2
Made with FlippingBook flipbook maker