Brand-Specific Bypass Valve Requirements Compared

Written by Craig "The Water Guy" Phillips

When comparing bypass valve requirements across major fire pump brands, we find key differences in placement, quantity, and valve type. Brands like Robert Bosch GmbH and Tescom Corp. specify normally open butterfly valves, while others vary on whether one or two bypass valves flank each check valve. NFPA 20 sets the baseline, but manufacturer guidance often goes further. Stick with us and we'll break down exactly what each approach means for your system.

Key Takeaways

• Robert Bosch GmbH requires normally open butterfly valves specifically for emergency pressure relief in fire pump bypass configurations.
• Tescom Corp. specifies normally open butterfly valves to ensure backup flow and maintain precise pressure control during pump operation.
• Bowman Power Group prioritizes unobstructed bypass lines using minimal-resistance valve designs to maintain system flow continuity.
• Most major fire pump brands install bypass valves on both sides of the check valve, enabling full isolation without pump shutdown.
• Some manufacturers still prefer single-valve simplicity, while others adopt dual-valve configurations for greater inspection flexibility and reliability.

What NFPA 20 Actually Requires for Fire Pump Bypass Valves

When it comes to bypass valves in fire pump systems, NFPA 20 is more specific than many engineers realize. Section 4.16.4.1 only mandates a bypass valve when city water supply pressure is sufficient to operate the system without the pump running. That's a critical distinction worth understanding.

NFPA 20 Section 4.18.1 also requires bypass valves to remain normally open, ensuring the bypass line is immediately available. Here's where it gets interesting—the code doesn't strictly require two control valves flanking the check valve, but appendix notes strongly recommend this arrangement for system maintenance without a full shutdown.

We can't overstate how much these nuances matter. Misreading NFPA 20 leads to over-engineered or under-protected fire pump system installations that create real operational headaches down the line.

How Major Fire Pump Brands Apply Bypass Valve Placement

Major fire pump brands don't just echo NFPA 20—they build on it with practical installation guidance that clarifies what the code leaves open to interpretation. Most leading manufacturers call for bypass valve installation on both sides of the check valve, giving technicians true isolation capability without taking the fire pump offline. That's a meaningful maintenance advantage.

Many brands also specify that these bypass valves remain normally open, preserving immediate flow control when system pressure demands it. You'll often find manufacturer manuals detailing exact valve placement relative to the check valve, ensuring that isolation during inspection or repair happens safely and efficiently.

When city water pressure supports the system, that placement becomes even more critical—and brand guidance tends to reflect exactly that operational reality.p>

One or Two Bypass Valves Per Check Valve:

How many bypass valves should wrap around a single check valve? The answer depends on which brand's installation manual you're following. Older brand-specific installation guidelines typically called for one normally closed bypass valve around each check valve.

Older brand-specific installation guidelines typically called for one normally closed bypass valve around each check valve.

Modern standards, however, are shifting toward two bypass valves—one on each side—dramatically improving operational flexibility.p>

Here's why that matters: with dual bypass valves, we can isolate and inspect the check valve independently from the pump, enabling more precise inspection and testing without compromising system availability. Single-valve arrangements limit that granularity.

We've seen certain manufacturers acknowledge that two valves increase system maintenance reliability while others still favor simplicity with one.

For mastery-level practitioners, understanding each brand-specific installation requirement guarantees we're never guessing when ITM demands precision.

Which Brands Require Normally Open Butterfly Valves and Why

Certain brands don't leave valve selection to interpretation—they specify normally open butterfly valves in bypass lines for deliberate, performance-driven reasons.

Robert Bosch GmbH uses them for emergency pressure relief, ensuring fail-safe flow when conditions demand immediate response. Tescom Corp. relies on normally open butterfly valves to maintain backup flow control and prevent pressure buildup during primary valve isolation.

Bowman Power Group prioritizes unobstructed bypass lines to minimize resistance in energy recovery systems.p>

Across these brands, the reasoning converges: normally open butterfly valves protect against pump dead-heading, prevent pressure surges, and preserve system continuity during maintenance or equipment isolation.

We're not looking at preference here—we're looking at engineered necessity. When bypass valves default to open, the system stays protected even when operators aren't actively managing flow.

How to Choose the Right Bypass Valve Configuration for Your Fire Pump

Choosing the right bypass valve configuration for your fire pump isn't guesswork—it's a decision that directly impacts system reliability, code compliance, and your ability to maintain the pump without interrupting protection.

Bypass valve configuration isn't guesswork—it directly determines system reliability, code compliance, and uninterrupted pump protection.

We recommend installing bypass valves on both sides of the check valve, giving you full operational flexibility during system maintenance. NFPA 20 calls for normally open positioning, so flow remains immediately available whenever you isolate the pump.

For valve configuration, butterfly or globe valves deliver the best balance of rapid operation and precise flow control. Don't undersize—your valve size must accommodate full pump flow to prevent pressure loss or cavitation.

When you treat each decision deliberately, your bypass valve becomes a genuine asset rather than an afterthought.

Frequently Asked Questions

Are All Bypass Valves the Same?

No, they're not! We find bypass valves vary widely in design, materials, pressure ratings, and controls. Each brand tailors them to specific applications, from simple mechanical setups to advanced electronic flow management systems.

What Is the 3 Rule for Pressure Relief Valves?

We use the 3 Rule to distribute total relieving capacity across three separate relief devices, ensuring no single valve handles more than one-third of required capacity, boosting redundancy and protecting against complete system overpressure failures.

What Are the ASME Standards for Valves?

We'll find ASME valve standards primarily in the B16 series and BPVC Section VIII. They govern dimensions, pressure ratings, materials, and testing—ensuring valves safely withstand 1.5 times maximum allowable working pressure across demanding industrial applications.

What Are the 4 Types of Valves?h3>

We've got four main valve types to know: gate valves for on/off service, globe valves for precise flow control, ball valves for quick shutoff, and butterfly valves for large-diameter pipe throttling.