Venturi-Flo distributors are one-piece units that utitlize a permanent
converging/diverging venturi to evenly apportion refrigerant. Venturi-Flo
distributors offer low pressure drop and can operate within a range of 50% to
200% of nominal capacity.
FEATURES, ADVANTAGES & BENEFITS
- Greater efficiency provides lower cost operation.
- Low pressure drop enables more accurate sizing of Thermo Expansion Valve, may
mean savings in valve sixe and cost.
- Ready-to-use construction saves time, and ensures easy installation
- High - Low load operation means Alco Venturi-Flo Distributors can operate
within a range of 50% to 200% of nominal capacity, reducing the number of
different distributors required to satisfy all applications, and improving the
chance of having the distributor needed
- Non-position sensitive distributor allows for easy mounting to existing
equipment
NOMENCLATURE
The Alco Venturi-Flo Distributors have been given type numbers which code the size inlet, size outlet and number of outlet tubes in the following manner: The first number indicates the inlet size in 1/8 of an inch; the second number indicates the outlet tube size in 1/16 of an inch; and the last number indicates the number of outlet tubes:
| Type Numbers |
| 9 |
3 |
12 |
9/8
1-1 /8 ODF inlet
|
3/16 ODF
outlets |
12 outlets |
Flare distributors are indicated by the prefix "F" in front of the first number. For example: F5-4-5 would have a 5/8 SAE female flare inlet and five 1/4" ODF outlets.
NOMINAL CAPACITIES
The nominal ratings for the Venturi-Flo distributor capacities are given in tons of refrigerant at various evaporator temperatures for R-12, R-22 and R-502. These ratings are based on a tube length of 36", a 15 PSI drop across the distributor, a 10 F Subcooled, vapor free, liquid refrigerant entering the expansion valve. The Keepflo distributor has an operating range from a minimum of 50% to a maximum of 200% of the nominal ratings. Do not exceed these limits without consulting the Keepflo Engineering Department. For example, a 9-3-10 distributor with a nominal rating of 8.8 tons R-22 at a 40°F evaporating temperature has a minimum capacity of 4.4 tons R-22 (50%) and a maximum capacity of 17.6 tons R-22 (200%).Please see below “ Sizing Venturi- Flo Distributor Section” to select distributors for all refrigerants.
APPLICATION
The Venturi-Flo distributor is available with both ODM and female flare nut inlet connections in the small sizes. All of the ODM inlets have been sized to fit directly into the outlet of Expansion valves at the proper capacity range.
SIZING A VENTURI-FLO DISTRIBUTOR
Required information:
1). Desired distributor tube diameter
2). Refrigerant Type
3). Number of distributor tube circuits
4). Evaporator capacity
5). Evaporator temperature
Selection Procedure:
1). In the Venturi-Flo distributor capacity table go to the # table section that corresponds to the desire circuit i tube diameter.
2). In the column labeled #of Outlets, find the row that I has the number that is equal to the number of ? desired distributor tube circuits.
3). Follow the row across the page until the capacity is found that corresponds to the desired refrigerant and evaporator temperature.
4). If the desired capacity falls within the range of 50% to 200% of the capacity found in Step 3 then this is the correct distributor.
5). If the desired capacity does not fall within the allowable range, then a different diameter distributor tube will have to be selected and the selection process has to start over at Step One.
6). Call factory for ordering information.
PRESSURE DROP
The pressure drop across the Alco Venturi-Flo Distributor will vary with load as shown in the following table:
| % Nominal
Load |
Pressure Drop
Psi |
| 250 |
40 |
| 150 |
25 |
| 125 |
20 |
| 100 |
15 |
| 75 |
10 |
| 50 |
7.5 |
OPERATION
The Venturi-Flo distributor consists of a converging section, a throat, and a diverging section as shown in Figure 2. The smooth contoured approach of the converging section (Point A) avoids separation of the refrigerant flow from the walls in the transition between the approach and the throat (Point B). The diverging section (Point C) following the throat is used to reduce the high throat velocity of the refrigerant, converting the velocity energy of the refrigerant back to pressure energy. Referring to Figure 1 and the pressure datum line at the top, the inlet pressure (P,) is reduced to a minimum pressure (P,) because of the throat, and from this point the pressure then increases to the value (P,) in the diverging section. The outlet pressure (P,) is less than the inlet pressure (P,) by an amount equal to the wall frictional losses. Thus the Venturi provides a smooth even refrigerant flow pattern with a minimum overall pressure loss.
Figure 1 illustrates the nozzle type distributor. The nozzle type consists of a straight approach to an orifice plate, which is a concentric hole in a metal plate. This distributor depends on the high pressure drop across the orifice and the resulting turbulence to provide distribution. The approaching refrigerant streamlines nearest the pipe walls (Point A) turns inward rather abruptly at the upstream face of the plate, and flows parallel to the plate toward the orifice. This parallel fluid flow continues past the edge of the orifice (Point B) and is swept along through the orifice by the center mass of the refrigerant flow. The refrigerant flow continues through the orifice with the minimum jet area (Point C) forming downstream of the orifice plate. The uncontrolled expansion in the large downstream section (unlike the Venturi with a controlled expansion) causes a turbulent pattern to be set up between the minimum jet area, the orifice plate and the walls (Point D). Thus with the orifice plate the velocity energy is not reconverted to pressure energy, but rather is dissipated in violent turbulence in the downstream section.
The Venturi-Flo distributor has two basic advantages over the orifice plate or pressure drop type. First of these is the pressure recovery feature which eliminates the high pressure drop common to the orifice plate type. This allows for closer and more economical valve sizing and more stable valve control. Secondly, the contour flow pattern channels the flow to the tubes which means even distribution; whereas, the orifice plate type depends upon pressure drop and the uncontrolled violent turbulence for distribution. Distributor tubing ends must be cut true, free from burrs, and thoroughly cleaned. For high temperature brazing of the copper distributor tubes to the brass distributor, a brazing alloy having an approximate melting-flow point of 1185°F - 1300°F, is recommended. A suitable flux should be used to prevent oxidation of the metal surfaces to be brazed. If the distributor tubes are to be joined to the distributor by soldering. CAUTION: The use of excessive heat may result in restricting or plugging the tubes wlth solder or brazing alloy. Indiscriminate use of brazing flux or soldering paste, if allowed to enter the system can be detrimental to the 3 operation of the refrigeration system and or control valves.
DISTRIBUTOR TUBE LENGTH
Distributor tubes must be of equal length for maximum distribution efficiency. Distributor tube lengths in excess of 36" will cause excessive pressure drops in the tubes with consequent losses in efficiency. Where lengths in excess of 36" are required, consult the Keepflo Inc. Engineering Department
Nozzle type distributors contain three components: a body, an interchangeable
orifice, and an orifice retaining ring. The primary advantage of Nonle type
distributors is flexibility. The interchangeable orifice enables the
distributor to be sized to different applications. Variables such as load,
range, evaporator temperature, and different refrigerants can be addressed by
simply changing the orifice without using another body.
Nomenclature
Nozzle Type distributors are described using four sets of numbers as follows: The first set describes the body type with the first digits indicating inlet diameter in 1/8 of an inch; the second set indicates the number of circuits; the third set indicates outlet tube diameter; and the last set indicates the orifice number. An example is shown below:
| Nozzle Type Distributors |
| 902 |
12 |
1/4 |
10 |
1 1/8 Dia. inlet 02
Style Body |
12 Circuits |
1/4" Outlet Dia. |
Orifice #10 |
Sizing An Orifice Type Distributor
Required information:
1).Refrigerant Type
2).Number of distributor tube circuits
3).Evaporator Capacity
4).Evaporator Temperature
Selection Procedure:
1). Determine the circuit loading. The circuit loading is found by dividing the evaporator capacity by the number of tube circuits.
2). Determine the tube diameter. The tube diameter is found by using the Table labeled Distributor Tube
Circuit Capacities.
a). Find the column that corresponds to the desired evaporator temperature and refrigerant type.
b). Go down the column and find the capacity that is the closest to the circuit capacity determined in step 1.
c). The tube diameter is then the diameter that corresponds to this capacity in the table.
3). Determine the correct distributor nozzle. The correct sized nozzle is found by using the table labeled Distributor Nozzle Capacities.
a). Find the column that corresponds to the desired refrigerant and evaporator temperature.
b). Go down this column until the capacity that is the closest to the evaporator capacity if found.
c). The nozzle size that is in the same row as the evaporator capacity found in Step 1 is then the correct sized nozzle.
4). Determine the body type. The body type is found by using the table where the body types are listed. The table used will depend on whether a flare connection or a sweat connection is desired.
a). Go down the column labeled Max. No. of Circuits until the row is found that shows the selected tube diameter and the required number of circuits.
b). Determine the corresponding body type number by looking in the column labeled TYPE.
c). To insure that the selected body type will handle the selected nozzle look in the same row but in the column labeled Nozzle Numbers Available to see if the selected nozzle will work with this body.
Performance correction factors
R-134a – 0.77 from R-22 performance
R-404A –1.07 from R-502 performance
R-507 – 1.08 from R-502 performance
R-402A – 1.07 from R-502 performance
R-410A – 1.01 from R-22 performance
R-401A – 0.65 from R-22 performance
R-407C – 1.01 from R-22 performance
PLEASE DOWN LOAD KEEPFLO DISTRIBUTOR PERFORMANCE SOFTWARE FROM WEB SITE FOR YOUR DISTRIBUTOR SELECTION & RATING.
NOTE: Please contact Factory for any special distributors not mentioned in our catalogue.
Application
The Nozzle Type distributor is available with both ODM and female flare nut
inlet connections in small sizes. All ODM inlets have been sized to fit
directly in the outlet of thermo valves.