Adams, Chassis Components, Pumpers

What Is Your Preference for Front LDH Connections?

Issue 12 and Volume 23.

BILL ADAMS

This question can be addressed from multiple viewpoints (sic). Based on my personal experience driving a pumper, I like a front suction (steamer) connection—with caveats. When taking the words “for front large-diameter hose (LDH) connections” literally, I am emphatically opposed to it if intended for that sole purpose. I have yet to see a pumper either forward lay or reverse lay LDH from the front bumper. Supply hose is deployed from the rear hosebed of the apparatus and being so I believe the connections to connect it to the fire pump should also be at the rear. The pump operator’s task of making an LDH connection to the pump for either a supply or discharge line should be safe, easy, and functional.

Using the front steamer to make a hookup is similar to using a side inlet or discharge. The pump operator has to calculate how much hose to pull or estimate what length pony suction to use. The line must be dragged around the rig (look out for the rear tires) possibly into a traffic lane, which in itself is an avoidable safety hazard. The evolution is time-consuming, subject to error in miscalculation, and inherently dangerous. And, LDH is heavy. However, if the front suction is to be used as a secondary LDH connection to supplement my preferred rear or nonpreferred side suction connection, then it has merit, and it would be acceptable. Many LDH users are under the false impression that a single LDH connection will always provide enough flow to supply a pump’s rated capacity. That’s a mistake.

DRAFTING

If a front suction is to be used primarily for drafting rather than an LDH connection, there are considerations that should be evaluated. The front steamer will not allow, for example, a 1,500 gallon-per-minute or larger fire pump to pump full capacity. Provided purchasers are aware of that limitation, and if it is firematically acceptable, then I say go for it. Purchasers should be conscious that some manufacturers’ claims of a front suction flow rate may not reflect reality. Sentence A.16.6.1 in National Fire Protection Association (NFPA) 1901, Standard for Automotive Fire Apparatus, states: “Intakes at the front or rear of the apparatus or otherwise specially situated might not allow drafting rated capacity at rated pressure. The purchaser should specify the flow rates required from auxiliary intakes, especially front and rear intakes or other intakes located 10 ft (3 m) or more away from the pump. If auxiliary intakes are provided, the purchaser should also consider requiring the manufacturer to certify the actual flow rates from auxiliary intakes.” That statement is in the standard for a reason. Purchasers should communicate with vendors to ascertain achievable flow rates prior to specifying one that is unreasonable and unattainable. Requesting third-party certification separates fact from fiction. Be safe; get it in writing. Manufacturers should have no objection because they don’t want to hear the words, “The front suction flow rate does not meet our specifications. Take the rig back.” If a front suction has proven firematically advantageous or is a necessity to reach drafting sites, a possibility is that a side steamer inlet can be used to augment a front steamer when drafting—if you have enough suction hose. There are numerous configurations available to pipe a front suction. Most are inefficient. Bear in mind that each fitting, turn, and bend in the piping increases friction loss. Although a swiveling elbow on top of an extended front bumper may facilitate “hooking up,” when drafting there is a decrease in efficiency.

BIG FIRE HOOKUPS

The front suction can be an invaluable asset when making a big fire hookup to a hydrant, especially when it is fitted with a preconnected soft suction and more so with a swiveling suction elbow on top of the bumper apron. Most pump operators who’ve pumped rigs without a swiveling elbow can attest to having to jockey the rig to remove kinks to the front steamer after the hydrant was charged. The swiveling elbow may not eliminate all kinks, but it helps greatly. Purchasers make a large investment for front suctions. Often, they can negate its operational efficiency by cramming 10 pounds of “stuff” onto a five-pound bumper. Adding preconnected attack lines, extra compartments, sirens, and a bell on a bumper may inadvertently decrease the speed and efficiency of making a big fire hookup.

DISADVANTAGES

If a front bumper must be extended to provide a front suction, the wall-to-wall turning radius of the rig is increased. Some purchasers’ and vendors’ specifications may not explicitly note if a specified turning radius is wall-to-wall or curb-to-curb. They should. There can be a big difference. Another consideration is the angle of approach. Specifications usually state the angle shall meet NFPA 1901 or may only note that the angle of approach is calculated to the bottom of a front bumper. Many times, drain lines—and even the suction piping itself—extend below the bottom of the bumper. Write specifications carefully. Or, don’t drive too fast off the fire station ramp or over speed bumps. You could feel a very expensive thump. Reputable vendors will inform purchasers if a bumper extension, piping, and bumper accoutrements will affect the front gross axle weight rating, which may require larger capacity and possibly more expensive chassis components. It could also affect the front-to-rear axle weight ratio. There are too many variables and options to consider to provide an accurate cost for a front suction other than to say it’s expensive. Purchasers should investigate and analyze the operational characteristics and financial impact of a front suction to ensure a justifiable return (value) for the monies expended.

BILL ADAMS is a member of the Fire Apparatus & Emergency Equipment Editorial Advisory Board, a former fire apparatus salesman, and a past chief of the East Rochester (NY) Fire Department. He has 50 years of experience in the volunteer fire service.