Precise, On-Line Pressure Protection

BV¾ /BV1	BV2	BV2 cutaway

Selection Guide

• Model BV¾ (ports are ¾-inch NPT tapped)
  Model BV1 (ports are 1-inch NPT tapped)
  
  These models are commonly used for cylinder-filling system. Either valve can be used
  with 1 ¼ or 1 ½-inch Blackmer pump models.
• Model BV1 ¼ (ports are 1 ¼-inch NPT tapped)
  Model BV1 ½ (ports are 1 ½-inch NPT tapped)
  
  These models are normally used for bobtail trucks and smaller bulk plant systems.
  Either valve can be used with 2 or 3-inch Blackmer pump models. Both valves are
  available with optional springs for use with the LGL 158 or LGLH2.
• Model BV2 (ports have 2-inch NPT companion flanges)
  
  The BV2 model is widely used for transports or larger bulk plant systems.
  It is recommended for use with 3 and 4-inch Blackmer pump models.

Blackmer differential bypass valves are designed to protect pumps and system components from excessive pressure damage, and no LP gas pump installation is complete without one. Blackmer offers five different models that provide full-flow pressure control to 250 U.S. gpm (946 lpm) at 120 psid (8.27 Bar). Installation is easy with NPT tapped ports in sizes from 3?4" to 2". All models are suitable for both LP gas and anhydrous ammonia service.

Technical Assistance
In some applications, selecting the right pump or compressor may require more detailed information than can be presented in this bulletin. Your Blackmer representative can help you find the correct equipment to ensure the best performance possible for your specific application.

Maximum flow-through valve

* Normal maximum bypass flow rates without significantly exceeding the set pressure limit.

In operation, Blackmer valves provide exceptionally close pressure control, even under widely varying bypass flow conditions. The performance curve in Figure 4 below shows how a Blackmer valve maintains a virtually constant pressure of 100 psi (6.89 Bar) even as the volume being bypassed rises from 10 gpm to 100 gpm (38-378 lpm). Although the curve is that of a BV11?2" valve, the precision it demonstrates is typical of any Blackmer valve.

Blackmer bypass valves have no small, easily plugged, sensing passages; and with only two moving parts, their operation is simple and reliable. They open precisely at the preset spring pressure, and they close smoothly and quietly, thanks to a patented dash-pot design. As shown in Figure 5, a small chamber in the valve stem fills with liquid when the valve opens. This liquid then provides a hydraulic cushion preventing the valve from slamming shut if pressure is suddenly released. It also minimizes chatter and valve seat wear when pressures hover around the crucial limit.