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Jockey Pump Sizing and Options

Pressure maintenance pumps (PMP), or jockey pumps (JP) as they are more commonly referred to, are an often incorrectly sized part of a fire pump system. Lets walk through the fundamentals. Why/When Required: To start with, technically you are not required to provide a jockey pump on all systems.  NFPA 20 section A.4.25 states " Pressure maintenance (jockey or make-up) pumps should be used where it is desirable to maintain a uniform or relatively high pressure on the fire protection system. "  The goal is to not shock the system with water hammer when the main fire pump starts. You don't want to be boosting the pressure from 10 psi to 150 psi. You want to be boosting the pressure in the 5-15 psi range. It is our recommendation that in almost all situations, a jockey pump should be provided to minimize pressure surges when the main fire pump starts. Jockey Pump Types: Jockey pumps are not required to be listed per NFPA 20-2010 section 4.25.1.  The failure of a jockey pump
Recent posts

New AC Fire Fuel Tank Sizes/Design - 2021

Starting immediately, AC Fire is offering a new diesel fuel tank design with more than double the current number of tank sizes available. In addition they will now come standard with emergency vents and a Tnemec N69 Crawford Red paint for better durability.  Link to PDF literature for new double-wall fuel tank on the AC Fire web-site. Also check out our blog post on Sizing Diesel Fuel Tanks or the Installation of Diesel Fuel Tanks for Fire Pumps if you want to learn more about the code requirements associated with diesel tanks. Please reach out if you need additional information.  

Fire Pump Rating (Size) Selection

Fire pump sizing is not like commercial pump sizing. We don't care about efficiency, and you order pumps in only specific sizes. This article touches upon some items to consider when picking a fire pump. In general, the first step is determining your system demand point. Discussion of how exactly you determine this is beyond the scope of this article and has a lot of nuance depending upon your site-specific needs. However, for simplicity let's assume that you have a dry-system in an attic with a demand point of 305 gpm (2535 sq ft x 0.10 gpm/sq ft x 1.20 overflow/imbalance factor). Rated Flow (gpm) Sizing The first item you must specify is the pump flow rate. Per NFPA 20 (2013 edition) table 4.8.2 pumps are only allowed to be listed with the following flow rates in gpm: 25, 50, 100, 150, 200, 250, 300, 400, 450, 500, 750, 1000, 1250, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000 So with our example demand of 305 gpm, would you go with a 300 or 400 gpm rated fire pump?

Diesel Exhaust Requirements

The exhaust from a diesel engine driving a fire pump is an often-overlooked item.  The high heat put out by the exhaust is a hazard to occupants and can greatly contribute to overheating the room itself. NFPA 20 (2013 edition), section 11.5 covers "Engine Exhaust" and should be carefully reviewed. However as a starting point, the following items should be considered. Exhaust Discharge Location The first step is to determine where you are going to discharge the exhaust gases. NFPA 20 section 11.5.3 for "exhaust discharge location" has the generic common-sense requirements of do not discharge where you might hurt people, damage the building, or directed on combustible materials. But very little specific requirements are provided. There is a loose reference in NFPA 20 back to NFPA 37 ( Standard for the Installation and Use of Stationary Combustion Engines and Gas Turbines ). In addition, the International Mechanical Code (IMC) section 915.1 directs us back to NFPA 3

UL 448 - Fire Pump Horse Power Changes

Effective November 1, 2019, Underwriters’ Laboratories (UL) Standard 448 has been revised to change the maximum horsepower required by the driver (electric motor or diesel engine) paired with a fire pump. The new requirement specifies that maximum brake-horsepower must be demonstrated during each performance test. If the maximum horsepower developed is greater than current motor or engine horsepower offering, the pump will fail testing under the new criteria. This is an industry-wide change, meaning compliance is required by all UL listed fire pump manufacturers. To maintain compliance with the Standard, driver requirements for numerous fire pumps have changed for all manufacturers with any orders shipped beginning November 1, 2019. Vertical turbine fire pumps, by the nature of their design, are not affected by the change in Standard. The UL448 Standard pertains only to centrifugal pumps, therefore positive displacement pumps, are not affected by this change.  FAQs Does this change in

New FM Global Fire Pump Marking Requirements

FM Global is updating their nameplate requirements for fire pumps. Nameplates for pumps manufactured after October 1, 2017 must now include the name of the pump driver and pump controller manufacturers and serial numbers per the sample below: "With the global expansion of our business, we have seen a dramatic increase in the number of FM Approved fire pumps and pump packages worldwide," notes Dave Fuller, manager of FM Approvals' fire protection group. "This means that more and more manufacturers must rely on multiple facilities for distribution and shipping, and with that have come additional challenges to ensuring complete FM Approved pump packages are being supplied. By requiring more details be included on the pump or pump package label, we are increasing the transparency of this requirement to the end user. This creates a stronger paper trail and easier verification, and will help all parties involved should there ever be a question about a specific fire pu

Diesel Engine Cooling Loops

Make sure you are in compliance with FM Global's requirements for cooling loops on diesel engines. FM Global  Approval Standard 1333  was updated in 30 Nov 2013, but compliance was not required until 1 April 2015. Clarke Fire has an excellent write-up on their web page that you can find here . But, we wanted to summarize the key requirements. FM Approval - Cooling loops are now required to be approved and therefore they will have the FM logo on a nameplate. Low Raw Water Flow Alarm - This switch is set to activate at 75% of the required flow rate. High Raw Water Temperature Alarm - This switch is set at 105F (40C).