Brochure

Parker Hannifin Corporation
Climate & Industrial Controls Group
Cleveland, OH
Catalog CIC-2003-1/US
Distributors and Flow Controls
200
Technical Information Venturi Low Pressure Drop Distributors
Venturi Low Pressure Drop Distributors
This style of distributor is designed on the venturi orifice
concept. The venturi orifice has basically three sections:
(1) the converging inlet
(2) the throat area
(3) diverging outlet.
Based on the continuity equation and Bernoulli equation,
as the liquid refrigerant enters section (1) the velocity of the
refrigerant begins to increase and the pressure begins to
decrease. This continues until a maximum velocity and a
minimum pressure is reached in the throat area, section
(2). After the refrigerant leaves section (2) and begins to
enter section (3), the diverging outlet, the velocity begins
to decrease and the pressure increases. The venturi orifice
creates a smooth transition from section (1) through
section (2) and then back to section (3) resulting in little
turbulence. The pressure of the refrigerant after leaving
section (3) is only slightly less than the inlet pressure. The
pressure loss is caused by frictional losses between the
distributor wall and the fluid boundary layer, and some
turbulence. Due to the low pressure loss and smooth
refrigerant flow pattern, the venturi distributor provides a
low pressure loss refrigerant disturbing device. UL Listing
115500.
Sizing Suggestions
Required system information:
1) system design capacity in tons of refrigerant
2) system design refrigerant
3) total number of circuits required
4) system design temperature
5) inlet tube size
Step A: Select the chart on the following pages that
matches the inlet tube size required.
Step B: Select the column that matches the total
number of circuits required.
Step C: Using the system capacity, select a dis-
tributor that matches both the system refrigerant
and design temperature.
Step D: Determine if the system design capacity
meets the 1/2 to twice the standard operating
capacity requirements.
Step E: If the standard operating capacity require-
ment is not met, repeat the selection process
utilizing either the next size smaller or larger inlet
tube size.
Flow through a Venturi low pressure drop distributor.
% Nominal Pressure Drop
Load psi
250 40
150 25
125 20
100 15
75 10
50 7.5
Capacities
Venturi type distributor capacities are supplied in tons of
refrigerant. The capacity is based on the following condi-
tions:
• a total distributor pressure drop of 15 psi
• liquid refrigerant subcooled 1°F at the expansion
device
• a refrigerant tube length of 36" or . 91 meters.
Note: Standard operating range is from 1/2 to twice the
capacity.