The dimensions of the capillary tube for a 1/2 HP compressor depend mainly on the refrigerant type and the evaporator temperature for the specific application.
Recommendations for 1/2 HP Capillary Tube Dimensions
- Length and Diameter: Both determine the overall restriction of the tube.
- Diameter Variations: A percentage change in diameter impacts flow more than an equivalent change in length.
- Flow Adjustments:
- Longer tubes slow the flow.
- Excessive length increases restriction and reduces flow, often becoming uneconomical and ineffective.
- Shorter lengths gradually increase flow until a critical point is reached where flow increases rapidly with further reductions in length.
General Guideline: Keep tube lengths between 5′ and 16′ to avoid operational issues.
Capillary Tube for 1/2 HP Compressor with R134a
Applications Based on Evaporator Temperature
| Application | Evaporator Temp. | Condensation Temp. |
|---|---|---|
| Low Pressure (LBP) | -23.3°C (-10°F) | 54.4°C (130°F) |
| Medium Pressure (MBP) | -6.7°C (20°F) | 54.4°C (130°F) |
| High Pressure (HBP) | 7.2°C (45°F) | 54.4°C (130°F) |
Source: Tecumseh
| HP | Application | Diameter (in) | Length (m) |
|---|---|---|---|
| 1/2 HP | LBP | 0.036 | 2.5 |
| 1/2 HP | HBP | 0.064 | 3.0 |
| 1/2 HP | MBP | 0.050 | 3.0 |
Capillary Tubes for 1/2 HP Compressor with R-410A
Used mainly in low-capacity air conditioning systems (~6000 Btu/h).
| HP | -10°F (-23.3°C) | 25°F (-3.89°C) | 45°F (7.2°C) |
|---|---|---|---|
| 1/2 HP | 0.042 in / 37″ | 0.049 in / 84″ | 0.049 in / 42″ |
| 1/2 HP (2 Tubes Each) | 0.031 in / 72″ | 0.031 in / 37″ | 0.042 in / 102″ |
Source: Industries JB
Capillary Tube for 1/2 HP Compressor with R404A
For Low Temperature Applications (-23°C)
| HP | Diameter (in) | Length (m) |
|---|---|---|
| 1/2 HP | 0.036 | 1.7 |
| 1400 Btu/h | 0.044 | 1.9 |
| 2500 Btu/h | 0.055 | 2.05 |
For Medium Temperature Applications (-6.7°C)
| Cooling Capacity | Diameter (in) | Length (m) |
|---|---|---|
| 3750 Btu/h | 0.059 | 1.79 |
| 5000 Btu/h | 0.063 | 1.41 |
Capillary Tube for 1/2 HP Compressor with R22
Used for cooling capacities between 6000 and 7000 Btu/h in air conditioning applications (T = 7°C).
At 6000 Btu/h, T = 7°C
| Length (m) | 0.48 | 0.67 | 0.83 | 1.46 | 2.06 |
|---|---|---|---|---|---|
| Diameter (in) | 0.044 | 0.047 | 0.049 | 0.055 | 0.059 |
Optimal: 2.06 m with a diameter of 0.059 in.
At 7000 Btu/h, T = 7°C
| Length (m) | 0.35 | 0.50 | 0.61 | 1.07 | 1.51 |
|—————-|——-|——-|——-|——-|
| Diameter (in) | 0.044 | 0.047 | 0.049 | 0.055 | 0.059 |
Source: Tecumseh
Capillary Tubes for 1/2 HP Compressor with R407C
| HP | Low Temp. (-10°F) | Medium Temp. (25°F) | High Temp. (45°F) |
|---|---|---|---|
| 1/2 HP | 0.042 in / 29″ | 0.049 in / 63″ | 0.049 in / 32″ |
| 2 Tubes: | 0.031 in / 56″ | 0.042 in / 119″ | 0.042 in / 78″ |
