Guide to Choosing Bray International Ball Valve Actuators

Valve torque is influenced by multiple factors including seat material, operating frequency, media type, and pipeline pressure. The following sections break down these variables to simplify actuator selection.

1. Determine Base Torque: Consult torque charts (provided later) corresponding to your valve seat material.
2. Assess Valve Torque: Cross-reference valve size and maximum operating pressure in torque tables. For unlisted pressures, select the next highest value (e.g., use 300 psi for 285 psi).
3. Application Factor: Use Chart 1 to identify the coefficient matching your media type (e.g., 1.3 for saturated steam). If multiple factors apply, use the highest value.
4. Design Factor: Refer to Chart 2 for valve design adjustments (e.g., 0.3 for V-port balls).
5. Frequency Factor: Chart 3 provides coefficients based on cycling frequency (e.g., 0.0 for daily operation).
6. Total Torque Factor: Sum the three coefficients: Total Factor = Application + Design + Frequency.
7. Calculate Total Torque: Multiply the base torque by the total factor.
8. Media Seal Units: If applicable, add supplemental torque from Chart 4.
9. Actuator Selection:
   • Pneumatic (Double-Acting): Choose a model where output torque at available air pressure exceeds requirements.
   • Pneumatic (Spring-Return): Verify both pneumatic and spring-end torques meet needs.
   • Electric: Apply a 1.2 safety multiplier before selecting.
10. Mounting Kit: Select appropriate hardware using manufacturer reference matrices.

Note: These factors assume standard conditions. Actual values may vary.

Scenario: 2-inch full-bore valve with Tek-Fil® seats, 200 psi saturated steam, cycling 4x daily.

1. Base torque: 380 lb-in (from tables)
2. Total factor: 1.3 (steam) + 0.0 (design) + 0.0 (frequency) = 1.3
3. Total torque: 380 × 1.3 = 494 lb-in
4. Actuator Options:
   • Pneumatic (80 psig): Model 83 (721 lb-in)
   • Electric: S70-006 (600 lb-in after 1.2× safety factor)

Floating ball valves exhibit characteristic torque curves: initial break-to-move torque (highest), reduced running torque (≈75% of break), and final end torque (≈90% of break). This pattern occurs during both opening and closing cycles.

Special considerations apply for RPTFE seats (+15% torque), UHMWPE seats (+62%), and cryogenic services. Always verify dynamic torque requirements for high-cycle applications.