Water tank & Storage vessel
Guangzhou Longkon Eco-Tech Limited

Diaphragm pressure tank

Update Time:2015-02-02 16:22:48


Diaphragm pressure tank


The diaphragm pressure tank buffer tank No tower water supply No tower water supply device There is no negative pressure water supply

The principle 

Diaphragm pressure tank

Diaphragm pressure tank is made of steel shell and the rubber diaphragm tank energy storage device, consisting of rubber diaphragm separates the water room  completely, when the external pressure of the water filling in the diaphragm pressure tank , the seal of the tank keep the  pressure and store energy, compressed gas expansion rubber diaphragm placed inside the water tank.
Pressure tank is mainly composed of valve cover, inflatable mouth, air bags, carbon steel tanks, flange, when its connected to the water system, the system pressure is greater than the tank.
The applicable scope of the diaphragm pressure tank:
Diaphragm pressure tank is widely used for conditioning circulating water regulator, evaporate the water supply system, heating system circulating water filling water regulator, hydrating zener fire water supply system, frequency conversion water supply voltage regulator, filling water of boiler, pressure type water supply, etc.

The characteristics of the diaphragm pressure tank
1. security elements: natural rubber diaphragm, diaphragm for food grade can be applied in drinking water systems;
2. eliminate noise: diaphragm pressure tank can effectively smooth water pressure fluctuations in the system, automatically eliminate pipe network;
3. long using time: rubber can relax more than 200000 times, a air flushing can keep using for a long time;
4. sealed performance is good: for airtight device of tank, not contact, to ensure the water quality pollution from the outside world.


Diaphragm pressure tank type selection calculation
Differential pressure type and frequency conversion water supply unit, must choose the diaphragm pressure tank in order to solve water pump frequent restart phenomenon.How to choose the pressure tank volume and pressure tank pressure level?Must have a basis of pressure tank has a capacity of still won't be able to solve the problem of water pump frequent restart.Pressure tank capacity must be according to the water pump flow, head and start frequency selection pressure tank pressure rating.
One, the volume calculation
Generally, the pump start times per hour and the power of a relational table is as follows:
Motor power (Kw) 5.5 5.5 7.5 Kw, 7.5 Kw below - 22 Kw 22-55 Kw
Startup time (time/hour) 30 20 August 12
1, the effective volume Vesp computation formula is as follows:
Vesp = 16.5 x Q/n, among them, the Q for pump flow, n start times per hour
2, according to the water pump start-up characteristic coefficient to calculate the effective capacity
Z = (Pi + 1.033)/(Pf) + 1.033
Z is made valid by means of flow coefficient, namely the known pump start-up pressure conditions, pressure tank capacity utilization ratio effectively.
Pi for the pump start-up pressure = actual head + + system required pressure line loss
Pf stop pump pressure is general Pi + = (1-2) kg/cm squared
3, according to the actual capacity Vesp and Z to calculate the pressure tank
N = Vesp/Z
Second, the stress level
General life water pressure tank used into 1.0 Mpa, 1.6 Mpa and 2.5 Mpa
According to the actual pump pressure range value of the selected correct matching pressure tank, pressure tank level must be greater than the pump pressure value.

Diaphragm pressure tank type parameters
Air pressure can adjust water not tank volume, but the air pressure tank pressure within the scope of the adjustment in this volume, the frequency conversion system, to maximize the use of air pressure tank volume, but the air pressure tank prefi lled gas pressure and pump start-up pressure lower limit is set to agree, so that when the air pressure inside the tank water pump to start after all added to the system.

Network variable frequency constant pressure water supply, such as: life values for P1 = 0.5 MPa, pressure limit (pump) restart pressure P2 = 0.15 MPa, under normal circumstances, assuming pipe network water at night to 15 l/h, water pump stop working at night at 7 h (22:00-5:00) calculation, water consumption of 105 l, so, if the air pressure tank within the scope of the P1 and P2 pressure regulation of water is more than 105 l, can ensure the pump sleep 7 hours, therefore, regulating water in slightly larger than 105 l pressure tank is more appropriate, if choose adjust water well beyond 105 l () the pressure range of pressure tank, while the pump intermittent time is longer, but has begun to enter the water phase, more than 7 hours sleep time is pointless, therefore, is not the greater the pressure tank volume the better the results.

Suppose you want to choose the air pressure tank volume V, pressure tank prefi lled pressure for P2, by Boyle (Robert Boyle) gas law, in a certain temperature under the gas pressure (P) and volume (V) the product is equal to the principle of constant。
The PV = constant value, P1 * V2 = P * V1 = P2 V
Among them: P = pneumatic tank prefi lled gas pressure
V = pneumatic tank volume (also for the initial state to the volume of a gas filling)
V1 = system pressure for P1 pressure jar of the volume of a gas
V2 = system pressure P2 when air pressure tank the volume of a gas
By above knowable, V1 V2 = 0.15 0.5 = 0.15 V
V1 = 0.3 V2, V2 = V
The adjustment of the pressure tank volume delta V = V - V1 = 0.7 V = 105 l
V = 150 l
That should choose the air pressure tank volume is 150 l, because of the limitation of pressure tank model, so choose by big choice is not small and nearby principle, to select the corresponding LiangBang pressure tank.Heating system (boiler, air conditioner, heat pump, water heater, etc.) the selection of the tank
V =
C = water in the system the total capacity (including boilers, pipes, radiator, etc.)
E = the thermal expansion coefficient of water (the system cooling water temperature and the highest temperature of boiler running water expansion rate difference), standard equipment in the e = 0.0359 (90 ℃)
P1 = pre filling of the tank pressure P2 = peak pressure of the system operation (that is, the system pressure relief valve in the takeoff) V = the volume of the tank

Different temperature expansion rate of the water
Temperature (℃) e temperature (℃) e temperature (℃) e temperature (℃) e
0 40 0.00782 65 0.0198 90 0.00013 0.0359
4 0 45 0.0099 70 0.0099 70 0.0396
10 50 0.0121 75 0.0258 100 0.00027 0.00027
20 55 0.0145 80 0.00177 0.029
30 60 85 0.0324 0.0171 0.00435
For example, total system water solvent for 400 l of boiler, pressure relief valve takeoff to 3 bar. Should choose how much volume of the tank
V = = = 38.3 L
According to choose big don't choose small and nearby principle, to select the corresponding pressure tank.

Empirical formula:

Air conditioner, heat pump systems: below 5 p machine in 2 l;5-10 p machine with 5 l;10 to 18 p machine with 8 l;1 p (horse) = 2.5 KW
Boiler, water heater system:

Power of 1000 kcal/h boiler or water heater, its water system total volume for 10 to 20 l;1 kcal/h (kcal/h) = 1.163 W
In the constant pressure system (frequency conversion water supply, constant pressure water supply tank selection, etc
To avoid water pump frequently, the regulation of the tank volume should satisfy a certain time of water pump flow rate (L/min), computation formula is as follows:
V = K * Amax *
Coefficient K = pump work, with the pump power, specific see table;1 kw = 1.341 HP HP = 0.735 kw
P (HP) 1 2 2-4-5-8-9-12 > 12
0.25 0.375 0.625 0.875 1 K
Amax = maximum flow of the pump (L/min)
Pmax = maximum working pressure of the pump (pump pressure) on the system downtime
Minimum working pressure Pmin = water pump (pump start-up pressure) on the system
Prefi lled Ppre = pressure tank pressure
V = pneumatic tank volume

For example, a constant pressure water supply pump power for 4 HP equipment, water pumps maximum flow is 120 l/min, the system pressure is lower than 2.2 bar will start automatically when the pump, the system pressure reaches 7 bar, water pump, automatic stop, air pressure tank prefi lled pressure of 2 bar, how to choose the system of air pressure tank?
By above knowable, pump power is 4 HP, K = 0.375
V = K * Amax * = * 120 * 0.375 = 80 l
According to choose big don't choose small and nearby principle, to select the corresponding pressure tank.