Work it out.
Calculators
Cooling capacity (sensible heat)
Q = m · c · ΔT
COP and EER for refrigeration systems
COP = Q_køl / P
Cooling requirement for a room (estimate)
Volumen × W/m³
CO2 equivalent for refrigerant charge
F-gas-forordning (EU) 2024/573, bilag I (GWP)
Statutory leak check interval
F-gas-forordning (EU) 2024/573, artikel 5 (lækagekontrol)
Superheat on the suction line
Overhedning = T_målt − T_mætning (køleteknisk servicepraksis)
Subcooling on the liquid line
Underkøling = T_mætning − T_målt (køleteknisk servicepraksis)
Refrigerant mass in a pipe section
Rørvolumen (geometri) × væskefylde (stofdata)
Test pressure for strength and leak testing
DS/EN 378-2:2016 (trykprøvning af køleanlæg)
Condensate from an air cooler
Massebalance for fugtig luft (Mollier h-x-diagram)
The compressor's theoretical swept volume
Volumetrisk virkningsgrad (køleteknisk grundbegreb)
Refrigerant velocity in a pipeline
Kontinuitetsligning + anbefalede rørhastigheder (køleteknisk praksis)
Defrost energy for an air cooler
Isens smeltevarme 334 kJ/kg (fysisk konstant)
Practical limit for refrigerant leaks
DS/EN 378-1, praktisk grænse (PL)
Cycle process from log p-h diagram
Refrigeration cycle energy balance (h, log p-diagram), enthalpies with IIR reference
Carnot COP and facility's coefficient of performance
Thermodynamics second law (Carnot process)
Cooling surface: power on air side
Energy balance for humid air (Mollier h-x-diagram), cp,air = 1.006 kJ/(kg·K)
Cold store: heat ingress through panels and from goods
DS 418 (U = 1 ÷ (Rsi + d/λ + Rse), Rsi + Rse = 0,17 m²K/W) + Q = m·c·ΔT
Square-to-round transition
Approximate flat pattern
Tee and lateral
Exact flat pattern
Breeches piece
Exact flat pattern
Segmented pipe elbow
Exact flat pattern
Two-part valve cover
Exact flat pattern
Nozzle with tab collar on a flat wall
Exact flat pattern
Pipe-to-square transition
Approximate flat pattern
Tools that work in all subjects
Whatever your programme is called, these tools calculate the same — Pythagoras, area, percentages and units are not tied to one trade.
- Pythagorasa² + b² = c²Find the missing side, set out a right angle, check whether a room is square, and find the space diagonal.
- Area and perimeterm²Rectangle, triangle, trapezium, circle and composite shapes — area and perimeter.
- Volume and surface aream³ · lBox, cylinder, cone, sphere, pyramid, prism, pipe and frustum — also in litres.
- Percent%Percentage of, how many per cent, percentage change, discount and VAT.
- Scale and ratios1 : 50From drawing to reality, area and volume to scale, the rule of three and dividing in a ratio.
- Unit convertermm ↔ mFrom mm to km, Pa to bar and kB to GB — with the unit staircase.
- Time calculations and the clockt : minTime between two clock times, add time, and 1.75 h = 1 h 45 min for the timesheet.
- Slope and fall% · ° · 1:xFall from level to level, in per cent, per mille, degrees and mm per metre — and the height difference.
- Material consumption including wastem² + %Boards, paint, battens at c/c spacing and packs — for a composite surface or a whole room, with waste.