Engine Operations›Master Stream Operations
Engine Company Operations 2023 V-1 · Chapter 7
STOP
Not an announcement — a confirmation. The manual makes it one of the things the coordinated effort on scene exists to guarantee.
Get the placement right the first time. Once the line is in operation the device must be shut down to be repositioned. There is no nudging it while it is flowing.
The corners are the safe positions. Setting up in front of the building — off the ground or off the top of the engine — is “a dangerous and ineffective tactic.” The crew is then in the collapse zone and may not have enough time to react to a sudden collapse of an exterior wall.
Collapse zone = 1.5 × the height of the tallest exterior wall. A store front with a 20-foot wall gets a 30-foot zone to account for falling or bouncing debris — the further the better.
Engine Company Operations 2023 V-1, ch.7 Master Stream Operations, pp.7-1–7-2“Master stream operations require a coordinated effort from the companies operating on scene, one of which is ensuring that all department members have been backed out of the building prior to flowing any master stream or elevated ladder pipe.”
“The master stream device must be properly positioned to provide an effective stream on a fire once the line is in operation, it must be shut down to be repositioned. The safest exterior positions to operate a master stream are at the corners of the building. Setting up a master stream in front of the building, whether it is being operated from the top of the engine or from the ground, is a dangerous and ineffective tactic. Firefighters operating the stream are now in the collapse zone and may not have enough time to react to a sudden collapse of an exterior wall.”
Engine Company Operations 2023 V-1, ch.7, p.7-1
“Should the need arise to operate a master stream from the front of a building, it should be set back far enough so that it will not be struck by any falling walls or debris. It is a widely accepted figure in the fire service that the collapse zone should be one and one-half times the height of the tallest exterior wall. A store front that has a 20-foot wall should have a collapse safety zone of 30 feet to account for falling or bouncing debris, the further the better.”
Engine Company Operations 2023 V-1, ch.7, p.7-2 — published as corrected prose; the printed sentence is missing a word and reads “so that is will not be struck.”
Over 350 gpm, and it needs mechanical assistance to handle.
That is the definition line. Below it you are on hand lines; above it you are running an appliance, not a nozzle in someone’s hands. Engine Company Operations 2023 V-1, ch.7, p.7-1
Also called large-caliber streams — LCS.
Long-reaching, high-volume. Same thing, different radio word. Engine Company Operations 2023 V-1, ch.7, p.7-1
Three forms: portable, elevated, apparatus-mounted.
Portable (sometimes called ground-based) · elevated, including ladder pipes and nozzles attached to elevating platforms · or mounted atop the engine apparatus itself. Engine Company Operations 2023 V-1, ch.7, p.7-1
You go to master streams for two reasons: the fire beat the hand lines, or the spot is no longer safe for members.
Usually defensive. The majority of structure fires an engine company sees are handled with hand lines; the master stream is for delivering large quantities of water from a great distance. Engine Company Operations 2023 V-1, ch.7, p.7-1
Putting one in service usually means the interior offensive operation has been abandoned.
A defensive posture is being employed. Treat the decision as a fireground posture change, not just a bigger nozzle. Engine Company Operations 2023 V-1, ch.7, p.7-1
“The majority of structure fires that an Engine Company will encounter can easily be handled with the use of hand-lines. On some occasions there will be a fire that cannot be controlled by handlines and will require the engine company to deliver large quantities of water from a great distance.”
“Master streams are deployed in situations, usually defensive, where the fire is beyond the ability to control with the use of hand lines or there is a need for fire streams in a location that is no longer safe for department members. By most definitions, any stream greater than 350 gpm and that requires mechanical assistance for handling is defined as a ‘master’ stream. Also called ‘large-caliber streams’ or LCS, these long-reaching, high-volume streams may be portable (sometimes called ‘ground-based’), elevated (including ladder pipes and nozzles attached to elevating platforms), or mounted atop the engine apparatus itself.”
Engine Company Operations 2023 V-1, ch.7, p.7-1 — corrected prose; the printed text hyphenates “mechan-ical” across a line break.
Corners first. Always.
The safest exterior positions to operate a master stream are at the corners of the building. Everything else on this page is downstream of that one decision. Engine Company Operations 2023 V-1, ch.7, p.7-1
The front of the building is dangerous and ineffective.
Both, and in that order. Ground-based or off the top of the engine makes no difference — the operators are standing in the collapse zone with no reaction time. Engine Company Operations 2023 V-1, ch.7, p.7-1
If the front cannot be avoided, set back 1.5 × the tallest wall.
20-foot wall → 30 feet. That figure accounts for debris that bounces, not just debris that falls — and the manual’s own comment is “the further the better.” Engine Company Operations 2023 V-1, ch.7, p.7-2
Shut down to reposition — so the first placement is the placement.
Walk it before you charge it. Sight the stream on the objective, check the throw, check what is over your head, then call for water. Engine Company Operations 2023 V-1, ch.7, p.7-1
Safety problem one: the flow tears debris off the building.
Higher flows are more likely to knock debris loose and send it through the air into people and apparatus. Park and stand accordingly. Engine Company Operations 2023 V-1, ch.7, p.7-1
Safety problem two: in portable mode the device will tip over.
A portable master stream has a limited side-to-side range. Turning the nozzle too far left or right can make the base unstable and tip it over. Reposition the base instead of over-swinging the nozzle — which means shutting it down. Engine Company Operations 2023 V-1, ch.7, p.7-1
“Master stream devices present several safety considerations that members must address during these types of operations. First there is an increased likelihood that the higher flows will knock debris loose from the building causing it to fly through the air and strike people or apparatus. Second, when operating in the portable mode the master stream has a limited side to side range that it can operate in. Turning the nozzle too far left or right may cause the base to become unstable and tip over.”
“When master streams are placed into service, it generally means that the interior offensive operations have been abandoned and a defensive posture is being employed.”
Engine Company Operations 2023 V-1, ch.7, p.7-1
On the truck side, the spot is chosen before the water is.
The Truck Manual builds aerial master streams into apparatus placement: spotting uninvolved to involved sets the truck up to protect uninvolved portions of the building “if anticipating using aerial master streams,” and taking an outside spot — rather than an inside one — “sets us up for aerial master stream operations should the need arise,” because it lets the engine get in close underneath and keeps the waterway out of the way. OFD Truck Manual v3.1, p.143 — apparatus placement
It sits nine to ten feet up, and that costs you at low angles.
A deck gun nozzle that high suffers a dramatic loss of effectiveness at low-angle operations. This is the single biggest limitation of the appliance. Engine Company Operations 2023 V-1, ch.7, p.7-2
On a narrow street, most of the water is wasted 25 to 30 feet inside.
Positioning limits imposed by narrow streets, plus the excessive height of the gun above the ground, means the stream hits the floor only 25 to 30 feet inside the structure. It never reaches the seat. Engine Company Operations 2023 V-1, ch.7, p.7-2
The Limiter Pin exists to stop you rotating the nozzle too low.
Know where it is before you need it. Engine Company Operations 2023 V-1, ch.7, p.7-2 — Photo 7-3
Best use: a quick, high-pressure hit through the window — then get the hand line in.
“The most effective operation in the use of the pre-connected deck gun is to direct a quick application of high-pressure water through the window to knock down the heavy fire while other member[s] get a handline into position by whatever means available.” Faster fire control means increased life safety for civilians and firefighters. Engine Company Operations 2023 V-1, ch.7, p.7-3
Upper floors are where the deck gun angle actually works for you.
The steeper stream angle reduces the chance of pushing fire through the compartment and out into the hallway. Most of the water strikes the ceiling of the fire compartment and coarse droplets rain down on the burning contents. Engine Company Operations 2023 V-1, ch.7, p.7-3
Smaller tip, shorter application — a 1½" tip for reach and water conservation.
Employing a smaller tip than normally used with a deck gun, and limiting the application of water, further reduces the danger of forcing fire out of the compartment of origin. The 1½" tip is used to generate the high-velocity pressure necessary for reach and to conserve water. Engine Company Operations 2023 V-1, ch.7, p.7-3
“One drawback with deck gun nozzles that sit as much as nine to 10 feet above the ground is a dramatic loss of effectiveness at low-angle operations. Taking into account the positioning limitations imposed by narrow streets combined with the excessive height of the deck gun above the ground, most of the water will be wasted as the stream hits the floor only 25 to 30 feet inside the structure.”
Engine Company Operations 2023 V-1, ch.7, p.7-2 — corrected prose; printed as “imposed by a narrow streets.”
“The most effective operation in the use of the pre-connected deck gun is to direct a quick application of high-pressure water through the window to knock down the heavy fire while other members get a handline into position by whatever means available. Faster fire control means increased life safety for civilians and firefighters. The stream angle at upper-floor operations reduces the chances of ‘pushing’ the fire throughout the compartment and out into the hallway. Most of the water strikes the ceiling of the fire compartment and coarse droplets rain down on the burning contents. Employing a smaller tip than normally used with a deck gun and limiting the application of water further reduces the danger of forcing the fire from the compartment of origin. A 1½-inch tip is used to generate the high-velocity pressure necessary for reach and to conserve water.”
Engine Company Operations 2023 V-1, ch.7, p.7-3
Appliance loss for a deck gun or ground monitor: 25 psi.
Goes in as the A term of PDP = F + E + A + N. OFD Hydraulic Manual — Appliance Loss, large appliances
Drilled as Evolution 1.4 — deck gun while flowing additional hand lines: flow the deck gun for a quick knockdown on the simulated fire using different smooth bore tip sizes, then transition to hydrant supply and flow a 2½" hand line at proper pressures. — ADO-Pumper task book, September 2024 Version, evolution 1.4. Evolution list on the Engine Operations home.
A monitor is two components: the nozzle and the base.
The nozzle is typically a combination fog nozzle, or a stacked set of smooth bore tips varying in size and gpm delivery. The base is a portable stand used to attach the stinger for remote operations — folding legs for stability, a single LDH inlet. Engine Company Operations 2023 V-1, ch.7, p.7-4
The Stinger is one appliance that does both jobs — deck gun or portable monitor.
A dual-purpose break-apart monitor. Mounted to a plumbed outlet on top of the engine with the nozzle assembly attached. Engine Company Operations 2023 V-1, ch.7, p.7-4
Plumbed means fast: no supply line to run before it flows.
That is the whole argument for using it in the deck-gun configuration. Based on the tip being used, the manual states the Stinger can deliver up to 1,250 gpm. Engine Company Operations 2023 V-1, ch.7, p.7-4
The cost of that speed: the engine has to be parked close.
A disadvantage of using the Stinger in the deck-gun configuration is that it may require the engine apparatus to be parked in close proximity to ensure proper reach — placing the engine in a potentially dangerous position. Read that against the collapse zone above before you commit the rig. Engine Company Operations 2023 V-1, ch.7, p.7-4
The nozzle assembly carries the hand wheel and an in-line pressure gauge.
It is the upper portion of the deck gun. Either a combination nozzle or a stacked tip set attaches to the assembly pipe; the hand wheel adjusts the angle of the tip. The same assembly affixes to either the engine or the portable base — that gauge goes with it. Engine Company Operations 2023 V-1, ch.7, p.7-4
Going remote is three moves: set up the base, pull the stinger, stretch the LDH.
The base is a lightweight portable stand with a 5" LDH inlet, normally stored in the rear compartment, and it can be set up at any desired location. The point of doing it: it removes the dangers of the fire from the apparatus and from any firefighters operating in the area. Engine Company Operations 2023 V-1, ch.7, p.7-5
“The two components that make up [a] monitor are the nozzle and the base. The nozzle is typically a combination fog nozzle, or a stacked set of smooth bore tips varying in size and GPM delivery may be attached. The base is a portable stand used to attach the stinger for remote operations. The base has folding legs for stability and a single LDH inlet.”
“The Stinger is a dual purpose break-apart Monitor that can be used as a deck gun or portable monitor. The Stinger is mounted to a plumbed outlet on the top of the engine with nozzle assembly attached. The fact that the Stinger is plumbed allows it to be placed into operation rapidly without having to run a supply line to it. Based on the tip being used the Stinger can deliver up to 1,250 gallons per minute of water. A disadvantage of using the Stinger in the deck-gun configuration is that it may require the engine apparatus to be parked in close proximity to ensure the proper reach, thus placing the engine in a potential dangerous position.”
“The nozzle assembly is the upper portion of the deck gun. Either a combination nozzle or stacked tip set can be attached to the nozzle assembly pipe. This assembly also includes a hand wheel for adjusting the angle of the tip and in-line pressure gauge. This assembly can be affixed to either the engine or to the portable base.”
Engine Company Operations 2023 V-1, ch.7, p.7-4 — corrected prose; printed as “A disadvantaged of using the Stinger.”
“In the event that the stinger needs to be set up for a remote operation, the monitor can be removed and attached to a base. The base uses a 5” LDH inlet to supply the monitor. The Base is a light weight portable stand used during a remote monitor operation. The base, normally stored in the rear compartment, can be remotely set up at any desired location and remove the dangers of the fire from the apparatus and any firefighters operating in the area. To use the base, simply set it up, remove the stinger from the engine and stretch the LDH supply line.”
Engine Company Operations 2023 V-1, ch.7, p.7-5 — corrected prose; a missing sentence break and a singular/plural defect repaired.
The R.A.M. and the Stinger’s portable base are different appliances.
Different devices, different appliance losses — 25 psi for a deck gun or ground monitor, 10 psi for the R.A.M. Do not let the phrase “portable monitor” make them one thing in your head at the panel. Engine Company Operations 2023 V-1, ch.7, pp.7-4–7-6 · OFD Hydraulic Manual — Appliance Loss
One firefighter deploys it, and it can be carried while charged.
Light, compact, large water delivery, easily deployed by one firefighter. The R.A.M. can be carried while attached to a charged line — that is what makes the advance possible. Engine Company Operations 2023 V-1, ch.7, p.7-6
It uses the reaction force to hold itself down.
A patent-pending hydraulic stability system harnesses reaction force to stabilize the monitor. Four fold-out forged aluminum legs with carbide-tipped ground spikes extend to the largest footprint in its class; the rear ground spikes are angled so the carbide tips grip the ground surface. Engine Company Operations 2023 V-1, ch.7, p.7-6
Stored pre-connected, U-shaped valve handle, safety strap with a pouch.
The waterway design lowers friction loss and produces consistent stream quality in all ranges of motion. Engine Company Operations 2023 V-1, ch.7, p.7-6
Supplied by 2½" or 3". Appliance loss 10 psi.
Smooth bore 1½", 1⅜", 1¼" or combination fog nozzles can be used to deliver fire streams. The 10 psi is the number that goes into the A term. Engine Company Operations 2023 V-1, ch.7, p.7-6 · OFD Hydraulic Manual — Appliance Loss
R.A.M. tip rows both Orem documents support
| Tip | Nozzle pressure | Flow |
|---|---|---|
| 1¼" smooth bore | 80 psi | 400 gpm |
| 1⅜" smooth bore | 80 psi | 500 gpm |
| Appliance loss | — | 10 psi |
Source: OFD Hydraulic Manual, Elkhart R.A.M. nozzle table · appliance loss confirmed at Engine Company Operations 2023 V-1, ch.7, p.7-6.
UNRESOLVED — verify at the rig, then committee
Engine Company Operations states a maximum delivery capability of 500 gpm at 75 psi nozzle pressure, and lists 1½" among the approved tips. ch.7, p.7-6
The OFD Hydraulic Manual’s own R.A.M. table lists 1½" at 80 psi = 600 gpm. Elkhart R.A.M. nozzle table
Both are Orem sources, so neither outranks the other. Until it is settled, no single R.A.M. ceiling is published here — use the two rows in the table above, which both documents agree on, and flag the 1½" row when you see it.
Offensive application
The R.A.M. is not only a defensive appliance.
Its use is well suited to interior offensive operations: a large amount of water with long reach, to achieve knockdown in a large building or a long hallway. Engine Company Operations 2023 V-1, ch.7, p.7-7
Two people advance it: one runs the monitor, one moves the hose.
One firefighter controls the monitor by shutting it down fully or halfway to move it forward; the other helps move the hoseline supplying it. Once in position, the monitor is fully opened again. That is the muscle-memory pattern — shut, step, set, open. Engine Company Operations 2023 V-1, ch.7, p.7-7
It transitions from exterior to interior with minimal personnel.
An exterior fire attack can be advanced inside the structure to accomplish an interior attack without adding a crew. Engine Company Operations 2023 V-1, ch.7, p.7-7
Once the bulk of the fire is out, extend a smaller line off it.
The R.A.M. then works like an extended lay from a 2½" shutoff — a large supply line is already in place and can easily supply a 2½" or 1¾" handline at lower gpm. Engine Company Operations 2023 V-1, ch.7, p.7-8
Where that pays off: garden apartments, strip malls, warehouses — anything with a long setback.
Long setbacks are exactly where a hand line stretch dies and a monitor with reach does not. Engine Company Operations 2023 V-1, ch.7, p.7-8
“R.A.M. is easily deployed and operated by a single firefighter. Its patent-pending hydraulic stability system harnesses reaction force to stabilize the monitor. Four fold-out forged aluminum legs with carbide-tipped ground spikes extend to the largest footprint in its class for exceptional stability. The rear ground spikes are angled to help the carbide tips grip the ground surface. The R.A.M. can be carried while attached to a charged line. Exclusive patent-pending design lowers friction loss and produces consistent stream quality in all ranges of motion. The R.A.M. can be stored pre-connected and features an ergonomic U-shaped valve handle. Attached safety strap includes storage pouch.”
“The Rapid Attack Monitor or R.A.M is a light weight, compact portable monitor that provides a rapid large water delivery capacity that is easily deployed by one firefighter. … It can be supplied with either 2½” or 3” hoselines. Due to the design of the waterway the R.A.M has minimal appliance loss of 10 psi. Smooth bore 1½”, 1 3/8”, 1¼” or combination fog nozzles can be used to deliver fire streams.”
Engine Company Operations 2023 V-1, ch.7, p.7-6 — corrected prose; printed as “It’s patent-pendinghydraulic stability system.” The maximum-delivery sentence from this page is held in the unresolved box above.
“Besides the defensive application for the R.A.M its use is well suited for interior offensive operations. This application provides the delivery of a large amount of water with long reach capabilities, allowing us to achieve knockdown in a large building or a long hallway. The R.A.M can easily be transitioned from an exterior fire attack to advancing inside the structure to accomplish an interior attack with minimal personnel. This advancement can be accomplished with a two-person attack team with one firefighter controlling the monitor by shutting it down fully or halfway to move it forward. The other firefighter can help move the hoseline supplying it. Once in position, the monitor can be fully opened again.”
Engine Company Operations 2023 V-1, ch.7, p.7-7
“Another advantage to the R.A.M is the ability to advance a smaller hoseline from it once the ‘bulk’ of the fire has been extinguished. The R.A.M becomes similar to an extended lay from a 2½” shutoff. The advantage here is a large supply line already in place that can easily supply a 2½” or 1¾” handline with lower gpms. A good application for this feature is with garden apartments, strip malls, warehouses and other occupancies with long setbacks.”
Engine Company Operations 2023 V-1, ch.7, p.7-8 — corrected prose; printed as “a extended lay.”
Drilled as Evolution 1.3: with the apparatus attached to a water supply, firefighters deploy 3" supply to the R.A.M. and call for water; flow water to the monitor using fog tip and smooth bore stacked tips. — ADO-Pumper task book, September 2024 Version, evolution 1.3. Evolution list on the Engine Operations home.
Appliance loss — the A term
| Appliance | Loss |
|---|---|
| Deck gun · ground monitor | 25 psi |
| Rapid Attack Monitor (R.A.M.) | 10 psi |
| Standpipe | 25 psi |
| Wye · gated wye · siamese · reducer · increaser — combined flow over 350 gpm | 10 psi |
| The same, under 350 gpm | 0 psi |
Source: OFD Hydraulic Manual — Appliance Loss, small and large appliances. Standpipe loss is 25 psi regardless of flow.
Aerial — name the rig, not just the appliance
Ladder 32 — pre-plumbed waterway: 25 psi ± elevation. One number, plus or minus the elevation of the tip.
The tiller — playpipe: build it up. Q² (condensed Q) for the 3" · plus the elevation of the ladder · plus a 15 psi appliance loss · plus nozzle pressure.
The Hydraulic Manual lists these under near-identical designations, which reads as one rig with two appliances. It is two rigs. Ask which one you are supplying before you calculate.
OFD Hydraulic Manual — Appliance Loss, aerial master stream. Rig naming per Jason’s 2026-08-30 ruling: the pre-plumbed waterway is on the rig now designated Ladder 32; the playpipe is the tiller’s.
Master stream smooth bore tips
| Tip | Nozzle pressure | Flow |
|---|---|---|
| 1⅜" | 80 psi | 500 gpm |
| 1½" | 80 psi | 600 gpm |
| 1¾" | 80 psi | 800 gpm |
| 2" | 80 psi | 1,000 gpm |
Source: OFD Hydraulic Manual — Know the Flow, solid stream / smooth bore tips, master streams column. Long form: GPM = 29.7 × d² × √NP.
Nozzle reaction — what the device has to hold
NR = 1.57 × d² × NP
1.57 is the constant · d is nozzle diameter in inches · NP is nozzle pressure in psi. Worked at 80 psi, the master stream nozzle pressure.
| Tip | Worked | Reaction | Field method (⅓ flow) |
|---|---|---|---|
| 1¼" | 1.57 × 1.5625 × 80 | 196 lb | 133 lb @ 400 gpm |
| 1⅜" | 1.57 × 1.891 × 80 | 237 lb | 167 lb @ 500 gpm |
| 1½" | 1.57 × 2.25 × 80 | 283 lb | 200 lb @ 600 gpm |
| 1¾" | 1.57 × 3.0625 × 80 | 385 lb | 267 lb @ 800 gpm |
| 2" | 1.57 × 4 × 80 | 502 lb | 333 lb @ 1,000 gpm |
Table scrolls sideways on a narrow screen. Both methods are the Hydraulic Manual’s: the formula, and the field method of ⅓ the flow. The field method is an estimate and reads low at 80 psi — it is a check, not the number. Source: OFD Hydraulic Manual — Nozzle Reaction, smoothbore nozzle.
Reaction is what the base has to absorb. It is the reason the portable device has a limited side-to-side range and will tip if the nozzle is swung too far left or right, and it is the force the R.A.M.’s stability system is designed to harness rather than fight.
Engine Company Operations 2023 V-1, ch.7, p.7-1 (tip-over) and p.7-6 (stability system) · OFD Hydraulic Manual — Nozzle Reaction
Fog straight stream uses a different formula: NR = .0505 × GPM × √NP, field method ½ the flow.
OFD Hydraulic Manual — Nozzle Reaction, fog
Supplying the ladder company
Evolution 1.9 — pump to a ladder company for an elevated stream. Communicate with the ladder company for apparatus placement, establish a water supply, and keep the distance between engine and truck to a minimum to hold friction loss down. Make contact with the truck company, connect with LDH, charge the LDH slowly, verify correct pressures, and monitor residual. — ADO-Pumper task book, September 2024 Version, evolution 1.9. Open Evolution 1.9 · the full PDP chain lives on Pump Operations.
“Portable monitor” is doing too much work as a phrase
The Stinger dropped onto its base is a portable monitor. The R.A.M. is a portable monitor. They are not the same appliance and they do not carry the same appliance loss — 25 psi against 10 psi. The task book’s evolution 1.3 is titled “place the portable monitor in service” but its stated objective is “pump to portable RAM monitor.” Say which device out loud on the radio and at the panel.
The two figures that decide the position
1.5 × the tallest exterior wall for the collapse zone, and shut down to reposition. Together they mean the walk-around happens before the water does. Corners first; the front only when there is no alternative, and then set well back.
Not covered by chapter 7
Chapter 7 does not give a pump discharge pressure for any master stream device, a tip complement for any Orem rig, or a flow ceiling for the deck gun. It also gives no elevated-stream procedure beyond the “all members backed out” requirement — the aerial numbers on this page come from the OFD Hydraulic Manual, and aerial placement from the Truck Manual.
Sources. Engine Company Operations 2023 V-1, chapter 7 “Master Stream Operations,” pp.7-1 to 7-8, in full · OFD Hydraulic Manual — Know the Flow, Appliance Loss, Nozzle Reaction · OFD Truck Manual v3.1, p.143 (apparatus placement) · ADO-Pumper task book, September 2024 Version, evolutions 1.3, 1.4 and 1.9. Typographical defects in chapter 7 are published corrected; every correction is named where it occurs.
Version: prototype · Last reviewed 2026-08-30 · Compiled by Engineer Jason Anderson