The bacteriological test that clears a disinfected new service before it is connected, after the pressure test and the chlorine holding periodIn: Water service and meter tap guide
Back-end fabric
The high-speed, low-latency network connecting the GPUs for training; the largest link count in the clusterIn: GPU network optics and cabling
Back-out plan
The written sequence to safely abort and restore the equipment to its starting stateIn: Data center MOP SOP EOP
Back-siphonage
Backflow caused by negative pressure in the supply pipe, which siphons water backwardIn: Cross-connection control
Back-siphonage / backpressure
The two backflow mechanisms: a pull from negative supply pressure, or a push from higher downstream pressureIn: Backflow assembly types
ANSI/ASHRAE Standard 135, the vendor-neutral building automation protocol, with BACnet/IP and MS/TP transports and an object modelIn: BMS and DDC controls commissioning
Barrier had no drainage and trapped water; drainable adds a WRB and a drainage gap behind the foamIn: Stucco and EIFS
Barrier-type device
A membrane or flap that opens to drainage and closes when dry, protecting the seal without adding water, listed to ASSE 1072In: Trap primer field guide
The frame and the surface that carry the whole load down to the ground or the structure without settlingIn: Mast-climbing work platform safety
Base plate, leveling, grout
The steel plate at the column base, set to elevation on leveling nuts or shims, with non-shrink grout packed under it for full bearingIn: Steel erection and connections
Bar bending schedule, the table of every bar by mark, size, length, shape, and quantityIn: Rebar detailing and the BBS
BBU
Battery backup unit, a rack-level battery that rides the load through a disturbance and the transfer to backup generationIn: Rack DC power distribution (HVDC)
A steel plate set in the wall and backed by blocking that supports a lighter fixture independent of the wall finishIn: Fixture carriers and supports guide
Bearing stratum
The firm soil layer the helices must reach to develop the design capacity; the depth to it is set by the soil, not the drawing.In: Helical piers and screw piles
A photo pair showing a subject before and after work or correction, ideally from the same angle, proving the change or the fixIn: Field photo documentation
Before-cover-up
A photo taken in the last moment work is visible, before concrete, drywall, ceiling, or backfill permanently conceals itIn: Field photo documentation
An enlarged base cut wider than the shaft to spread end bearing over more area, where the soil holds the shapeIn: Drilled piers and caissons
Belleville washer
A conical disc spring on the joint bolt that holds clamping force through thermal cyclingIn: Busway installation field guide
Bellows
The flexible membrane loop over a closed-cell foam core that compresses and stretches to absorb the joint's movement, commonly EPDM at 60 milIn: Roof expansion joint installation
Keeping the belt centered; the belt moves toward the end of the roller it contacts first, so square and level control itIn: Conveyor system installation
Belt vs roller vs screw
Belt carries on a moving belt, roller on driven or gravity rollers, screw on an auger flight in a troughIn: Conveyor system installation
Battery energy storage system and its power conversion system, the inverter that moves energy in and outIn: Data center power commissioning
Best efficiency point (BEP)
The flow at which a pump runs at peak efficiency, quietest, and with the least wear; select the duty point near itIn: Hydronic pump install field guide
Building information modeling, the construction model used to design, coordinate, and build the project, which feeds the twinIn: Digital twin for operations
BIM vs VDC
BIM is the information-rich 3D model; VDC is the process of using that model to plan, coordinate, and build the workIn: BIM VDC coordination
Binder / emulsion
The sprayed asphalt that holds the chips; commonly a rapid-setting emulsion like CRS-2 or HFRS-2In: Chip seal surface treatment
Binder / intermediate course
The structural mix lift between surface and base; coarser, carries load and levelsIn: Asphalt mix types by layer
Binder grade bump
Dropping the virgin binder one grade softer to offset the stiffness RAP adds to the blendIn: Asphalt recycling and FDR
Binder plus EPDM / SBR
Polyurethane glue carrying colored EPDM top granules and recycled SBR base granulesIn: Running track surfacing
A treatment that controls bacteria and slime, which clog passages and drive under-deposit corrosion, especially in glycol loopsIn: Hydronic water and glycol field guide
Biocide / biofouling
Biofouling is biological growth and biofilm in the loop; the biocide is the additive that kills it before it formsIn: Liquid cooling loop chemistry
Biofall
Biological waterfall filter at the head of the falls that grows nutrient-eating bacteriaIn: Water feature installation
Biofilm
The bacterial film of soap, skin, and food in a drain that smells like sewage but is the drain, not the sewerIn: Sewer gas odor field guide
Biohazard remediation
Cleaning and decontaminating a scene fouled with blood, bodily fluids, sewage, or other infectious material so it is safe to use againIn: Biohazard and trauma cleanup guide
The treated, stabilized solid byproduct of wastewater treatment, handled for land application, landfill, or incinerationIn: Treatment plant systems field guide
Biotic stress
Damage from living causes, insects and diseases, usually secondary to an already stressed plantIn: Plant health care (PHC)
Biotic vs abiotic
A living cause (insect, disease, weed) versus a non-living one (drought, compaction, salt, chemical)In: Landscape IPM field guide
Bird stop
A formed eave closure that seals the open ends of a high-profile tile against birds, pests, and wind-driven rainIn: Tile roof installation
An expansion tank with a replaceable bladder that holds the water off the steel shell, separate from the air chargeIn: Hydronic water and glycol field guide
Blameless post-mortem
The review that focuses on the systemic conditions that allowed the incident, never on punishing an individual, so people tell the truthIn: Incident management and outage response
Binder rising through the chips to a slick black film, the too-much-binder failureIn: Chip seal surface treatment
Blend
Two or more cultivars of the same grass species planted togetherIn: Turfgrass selection
Blind / blank
A solid plate isolating the test section at a boundary, used instead of relying on a valve seatIn: Chilled water hydro test package
Blind spot / blind zone
The area around equipment the operator cannot see, largest directly behind a backing machineIn: Struck-by and caught-in hazards
Blind spot / kill zone
The area around a machine the operator cannot see, and the close-in ground where an unseen worker on foot is most likely to be struck, especially behind a backing machine.In: Proximity warning and struck-by safety tech
Blindside / pre-applied
Membrane installed before the pour, against shoring or a mud mat, bonding to the concreteIn: Below-grade waterproofing
Solid backing inside the wall framing, set before the drywall, that the cabinets and wall-hung work anchor intoIn: Millwork and casework install
Blocking / backing
Wood or steel set in the open wall at rough-in to give grab bars and wall-hung fixtures something solid to anchor toIn: Fixture rough-in and setting guide
Bloodborne pathogens / 1910.1030
Infectious agents in blood such as HBV, HCV, and HIV; 29 CFR 1910.1030 is OSHA's standard for occupational exposure to themIn: Biohazard and trauma cleanup guide
Bloom succession
Overlapping flowering so forage is continuous from spring through fall, with no dead monthsIn: Native and pollinator planting
Blow count
The number of hammer blows to advance the pile a foot or an inch, the field read on capacityIn: Driven pile foundations
Building management or automation system, the supervisory layer; direct digital control, the field controllers and logic underneath itIn: BMS and DDC controls commissioning
BMS / DCIM integration
Tying the detection to the building and data center management systems so a leak alarms, locates, and drives a shutdownIn: Liquid-cooling leak detection
BOD
Basis of design, the design team's documented assumptions and decisions for how the design meets the OPRIn: Data center commissioning process
Permanent joining of metal parts to establish electrical continuity, for equal potential and a fault path back to the sourceIn: Grounding vs bonding explained
Bonding adhesive
Contact adhesive that glues the membrane to the substrate on a fully adhered roof, not a seam productIn: EPDM rubber roof installation
A bushing with a lug or setscrew to land a bonding jumper, used to carry the ground around a concentric or eccentric knockoutIn: Conduit bodies and fittings
Articulating or telescopic MEWP that extends the platform out and up beyond the baseIn: Aerial lift and MEWP safety
Boom pump
Truck-mounted pump with a hydraulic, remote-controlled arm carrying the line to the placementIn: Concrete pumping and placement
Booster heater
A heater that raises a high-temperature dishmachine's final rinse water to the sanitizing temperature, commonly near 180 F per the NSF listingIn: Kitchen equipment install field guide
Booster pump
A pump set that raises the incoming supply pressure to a setpoint to reach fixtures the street pressure cannot serveIn: Booster and PRV system guide
Joining copper with a filler melting above about 840 F, stronger than solder, with a nitrogen purge on refrigeration and medical gasIn: Pipe joining methods
Breach
A hole, puncture, open seam, or other discontinuity in the membrane that lets water and current throughIn: Electronic leak detection
Break / cure
The emulsion turning from brown to black as water leaves; paving before it breaks traps water and kills the bondIn: Asphalt mill and overlay
Break / set
When the emulsion's water separates and leaves the asphalt to cure and grab the stoneIn: Chip seal surface treatment
Break and set
The point the emulsion releases its water and the mix gains strength; by evaporation for slurry, by chemistry for microIn: Slurry seal and micro-surfacing
The price, or markup, that just covers direct cost plus the job's share of overhead, with zero profit. Below it the job loses money.In: Overhead recovery and bid markup
Deer or rabbits eating foliage, stems, and buds; deer leave a torn ragged end, rabbits a clean angled cutIn: Deer and wildlife protection
Browse line
An even height, around 5 to 6 ft, to which deer have eaten the lower canopy across a property, a sign of sustained pressureIn: Deer and wildlife protection
The shell separating conditioned space from the weather: walls, roof, floors, windows, and the joints between themIn: Building insulation and air sealing
High-current conductor running the height of the rack that carries the shelf's DC output to the trays via blind-mate connectorsIn: Rack DC power distribution (HVDC)