Airnovation Engineering Pte Ltd
Pressure Relief Valve Calculator
Prefilled values are example assumptions, not design standards. Verify temperature-change rate, panel pressure limit and manufacturer operating limits before use.
Calculation Mode
Input Parameters (Floor Area × Height)
Input Parameters (Power Based)
Manufacturer-confirmed minimum operating temperature, not a full operating range; heated versions only. Confirm other temperatures, unheated versions and installation conditions with the manufacturer (FERMOD PRV(1).pdf, p. 3).
Manufacturer-confirmed minimum operating temperature for heated versions only, not a full operating range. Power-based selection remains unavailable.
The temperatures shown are two flow-data points from this table, not a manufacturer-confirmed full operating range. TN = positive-temperature; BT = low-temperature. Verify other product versions separately; do not apply the newer version’s −40°C rating to this table.
Opt-in assumption only, not a manufacturer-guaranteed curve or standard. No interpolation. Outside the selected model’s table range, quantity is unavailable.
Source: Intertecnica Air-Flow-Technical-Data-Sheet.pdf, p. 1. Pressure (Pa) is not specified in this sheet: flow selection only, not a panel-pressure safety check.
Calculation Results
Calculated Volume (Area × H)
0.00 m³
Required Total Airflow
0.00 m³/h
Required Relief Ports
0
(Raw: 0.00, rounded up)
Formula & Engineering Principles
1. Basic Principle: Why is Pressure Equalization Needed?
A cold room is essentially a sealed container. When the air inside cools down or heats up rapidly during refrigeration or defrost cycles, a significant pressure differential is created between the inside and outside due to thermal expansion and contraction. Without a relief valve to balance this pressure, the insulated panels can be sucked inwards (vacuum) or pushed outwards (overpressure), leading to structural damage. This calculator is designed to determine the required relief capacity to protect the structural integrity of the panels.
2. Calculation Methods Explained
For all volume-based methods, enter the internal floor area A in m² and internal height H in m. The calculator derives the volume automatically:
V (m³) = A (m²) × H (m)
FERMOD — By Valve Model
This mode uses the selected FERMOD model and calculation-pressure coefficient, not universal valve units. Airflow is an approximate thermal demand; quantity is calculated separately using the manufacturer formula:
Step 1: Calculate Required Total Airflow (m³/h)
Airflow ≈ (V × 60) / (T_rate × (273.15 + t_room))
Step 2: Calculate Required Number of Valves (n)
N = ceil((K × V) / (T_rate × (273 + t_room)))
- Airflow: Represents the theoretical volume of air per hour (the "demand") the cold room needs to exchange to maintain pressure balance.
- n: The calculated number of valves for the selected FERMOD model, always rounded upward.
- K: A model-specific manufacturer coefficient: 2220/2227 K=5.5 @ 200 Pa and 4.5 @ 300 Pa; 2230: 2 / 1.3; 2260: 0.47 / 0.37. These pressures are calculation points, not valve maximum ratings.
- V: The total internal volume of the cold room (m³), calculated as floor area A × height H.
- T_rate: The rate of temperature change, in **minutes per °C** (min/°C). A smaller value means a faster change.
- t_room: The lowest operating temperature in the room (°C).
By Equipment Power
Calculation is unavailable: the original kW lookup table has no verified source or applicability limits. Its former silent cap above 350 kW must not be used. Obtain an applicable manufacturer table before selecting quantities by power.
Intertecnica Method
This method is specific to the Intertecnica brand. It directly calculates the required airflow demand in "liters per minute" for selection against their product datasheet.
Q (lt/min) = 3.66 × V × Δt
- Q: The required airflow in **liters per minute (lt/min)**.
- 3.66: A fixed constant used by Intertecnica.
- V: The total internal volume of the cold room (m³), calculated as floor area A × height H.
- Δt: The rate of temperature change, in **°C per minute (°C/min)**. This definition is the inverse of T_rate; a larger value means a faster change.
Source: Intertecnica Air-Flow-Technical-Data-Sheet.pdf, p. 1. At +10/+1 °C (TN) or 0/−30 °C (BT), use the exact table capacity C in L/min. Quantity N = ceil(ceil(Q) / C). The sheet instructs rounding upward; this calculator conservatively rounds demand upward to whole L/min before selection, never down (the sheet’s 60 m³ × 2 °C/min example prints 439, while the formula gives 439.2). With these integer capacities, this gives the same quantity as ceil(Q / C).
For intermediate temperatures only, an explicit opt-in permits the lower of the model’s two endpoint capacities as a preliminary assumption—not interpolation or a manufacturer-guaranteed curve. Outside that table range, no quantity is given. No uniform safety factor is invented; confirm suitability, installation and any additional valve allowance with the manufacturer. MicroElebar is excluded because this sheet supplies no capacity row.
The source gives no pressure (Pa) basis for these flow capacities. Results are flow-based selections, not a panel-pressure safety verification or design approval.
Fermod reference: DOCSOUPAPES092026, quantity formula and model coefficients. Manufacturer arithmetic examples are not substituted for the formula. Results are conditional calculations, not design approval.