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Parameter in terms of which to specify the boundary between the laminar and turbulent flow regimes. The pressure ratio of the default parameterization is defined as the gauge pressure at the outlet divided by the same at the inlet.

Shut-offValveSMC

The block uses this data to construct a lookup table by which to determine from the pressure differential the reducing-valve opening area. Data is handled with linear interpolation (within the tabulated data range) and nearest-neighbor extrapolation (outside of the range).

βCrit is the value of the Laminar flow pressure ratio block parameter.

SMax is the value specified in the Maximum passage area block parameter.

By default, the valve opening dynamics are ignored. The valves are each assumed to respond instantaneously to changes in the pressure drop, without time lag between the onset of a pressure disturbance and the increased valve opening that the disturbance produces. If such time lags are of consequence in a model, you can capture them by setting the Opening dynamics block parameter to Include valve opening dynamics. The valves then open each at a rate given by the expression:

ReCrit is the value of the Critical Reynolds number block parameter.

ΔpReg is the value specified in the Valve regulation range block parameter.

The causes of the pressure losses incurred in the passages of the composite valve are ignored in the block. Whatever their natures—sudden area changes, flow passage contortions—only their cumulative effect is considered during simulation. This effect is captured in the block by the discharge coefficient, a measure of the flow rate through a valve relative to the theoretical value that it would have in the ideal case. The flow rates through each of the elementary valves are defined as:

This parameter is active when the Opening area parameterization block parameter is set to Linear area-pressure relationship.

This parameter is active when the Opening area parameterization block parameter is set to Tabulated data - Area vs. pressure.

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Although the valves are supposed to be visible, a previous owner may not have thought about the shut-off valves for water pipes when they performed DIY renovations. If that’s the case, be sure to have the city’s phone number on hand, so a technician can quickly come turn the water valve off at the street during an emergency.

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Smoothing factor for easing the transition to the fully open or fully closed valve position. The smoothing enhances the numerical robustness of the model, helping to avoid numerical errors due to discontinuities and simulation slowdowns due to zero crossings. Use this parameter to scale the widths of the smoothed regions. The smaller the value, the broader the transition.

Setting this parameter to the alternative Do not include valve opening dynamics is equivalent to specifying a value of 0 for the opening time constant. The opening area is in this case assumed to reach its new steady-state value instantaneously.

pAvg is the average of the gauge pressures at the ports (P and A or A and T).

Imagine this scenario: You’ve just walked in from a long day at work only to be greeted with the sound of running water and squishing beneath your feet. You have a burst pipe. And, therefore, you have a big problem on your hands. Rather than let the water continue spewing out and making the damage—and your cost to fix it—worse while you wait for the plumber to come, you’ll want to close your inside main water valve to ensure the water stops flowing.

Vector of opening areas corresponding to the breakpoints defined in the Pressure differential vector for reducing valve block parameter. The vector elements must decrease monotonically from left to right (with increasing pressure). For best results, avoid regions of flattened slope.

This parameter is active when the Opening area parameterization block parameter is set to Linear area-pressure relationship.

This parameter is active when the Opening dynamics block parameter is set to Include valve opening dynamics.

Shut off valvefunction

Area normal to the direction of flow within the pressure-relief valve at the start of simulation. The block uses this parameter to calculate the initial rate at which the pressure-relief valve is opening and from it the instantaneous opening area at the next time step.

This parameter is active when the Opening area parameterization block parameter is set to Tabulated data - Area vs. pressure.

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If the Valve parameterization block parameter is in the default setting of Linear area-opening relationship, the opening area of the pressure-reducing valve (P-A) is computed as:

Vector of pressure drops from port A to port T at which to specify the opening area of the valve. The vector elements must increase monotonically from left to right. This order is important when specifying the Opening area vector for relief valve block parameter.

As you know, your home is full of plumbing. There are pipes running behind your walls and under your floors that direct water to and from your plumbing accessories, such as faucets, toilets, and bathtubs. Although most, if not all, of your accessories have their own shut-off valves located close to them (such as your water heater’s shut-off valve), there is a way to ensure all the house’s plumbing is turned off at one time. The main valve turns off water to the house, so you don’t need to adjust each accessory individually.

This parameter is active when the Opening dynamics block parameter is set to Include valve opening dynamics.

Shut off valveaircraft

No one ever wants to see water from a burst pipe filling your home, but sometimes this nerve-wracking event can happen. That’s why it’s important to learn how to turn off the water to your house to limit the damage.

Opening area of each valve when fully open. The pressure-reducing and pressure-relief valves are assumed to be identical in size. See the block description for the pressure conditions under which the valves can each be said to be fully open.

Likewise, if you plan to do any remodeling to your home or dive into any plumbing ventures, such as replacing old pipes, you’ll want to make sure to turn off water to the house during the projects. This way, water buildup won’t occur as the result of a burst pipe during demolition or construction.

New Jersey Residents: The product being offered is a service contract and is separate and distinct from any product or service warranty which may be provided by the home builder or manufacturer.

where SAT is a tabulated function constructed from the Pressure drop vector and Opening area vector block parameters. The function is based on linear interpolation (for points within the data range) and nearest-neighbor extrapolation (for points outside the data range). The leakage and maximum opening areas are the minimum and maximum values of the Valve opening area vector block parameter. Opening area in the Tabulated data - Area vs. pressure parameterization

ƛ is the value of the Valve opening adjustment coefficient block parameter, a measure of the smoothing to apply to the valve transitions. The smaller the value, the smoother the transition.

Shut off Valve12V

q is the volumetric flow rate through the valve (P-A or A-T)..

Area normal to the direction of flow within the pressure-reducing valve at the start of simulation. The block uses this parameter to calculate the initial rate at which the pressure-reducing valve is opening and from it the instantaneous opening area at the next time step.

Vector of opening areas corresponding to the breakpoints defined in the Pressure differential vector for relief valve block parameter. The vector elements must decrease monotonically from left to right (with increasing pressure). For best results, avoid regions of flattened slope.

Shut off valvehydraulic

Pressure differential in excess of that required to fully close the pressure-reducing valve at which the pressure-relief valve first opens. The greater the transition pressure, the greater the lag between the closing of the pressure-reducing valve and the opening of its pressure-relief counterpart.

This parameter is active when the Opening dynamics block parameter is set to Include valve opening dynamics.

This parameter is active when the Opening area parameterization block parameter is set to Tabulated data - Area vs. pressure.

Shut-offvalvesymbol

The primary purpose of the leakage area of a closed valve is to ensure that at no time does a portion of the hydraulic network become isolated from the remainder of the model. Such isolated portions reduce the numerical robustness of the model and can slow down simulation or cause it to fail. Leakage is generally present in minuscule amounts in real valves but in a model its exact value is less important than it being a small number greater than zero. The leakage area is obtained from the block parameter of the same name.

Pressure differential from port A to port T that the composite valve is to maintain. The pressure-reducing valve closes in proportion to the pressure differential if its value should exceed that specified here. The pressure-relief valve opens in proportion to the same if its value should exceed, by an amount given by the Transition pressure block parameter, that needed to fully close the reducing valve.

Pressure ratio at which the flow is assumed to transition between laminar and turbulent regimes. The pressure ratio is defined as the gauge pressure at the outlet divided by the same at the inlet. The transition is assumed to be smooth and centered on this value.

This parameter is active when the Laminar transition specification block parameter is set to Reynolds number.

The valve opening areas are functions of the pressure differential from port A to port T—either directly proportional to it or general (tabulated) functions of it. The opening areas can each vary up to a point—the limit of the respective valve regulation range—beyond which the valve is saturated at full capacity and unable to counteract any additional pressure rises.

Include opening dynamics to more accurately capture the behavior of a real valve. For best real-time simulation performance, use with a local solver or disable valve opening dynamics altogether.

This parameter is active when the Laminar transition specification block parameter is set to Pressure ratio.

Ratio of the actual flow rate through the valve to the theoretical value that it would have in an ideal valve. This semi-empirical parameter measures the flow allowed through the valve: the greater its value, the greater the flow rate. Refer to the valve data sheet, if available, for this parameter. The value specified here is shared by both pressure-reducing and pressure-relief valves.

The opening area calculation depends on the valve parameterization selected for the block: either Linear area-opening relationship or Tabulated data - Area vs. pressure.

This parameter is active when the Opening area parameterization block parameter is set to Tabulated data - Area vs. pressure.

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where τ is a measure of the time needed for the instantaneous opening area (subscript In) to reach a new steady-state value (subscript SS).

Pressure differential interval over which the valves are each designed to operate. This interval spans those pressures over which the opening area changes between its minimum and maximum values. The value specified here applies to both the pressure-reducing and pressure-relief valves.

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with ΔpSet being the value of the Reducing valve pressure setting block parameter.

Shut-offvalveDanfoss

This parameter is active when the Opening area parameterization block parameter is set to Linear area-pressure relationship.

with ΔpTran being the transition pressure differential—that required for the pressure-relief valve to open after the pressure-reducing valve has fully closed. This value is obtained from the Transition pressure block parameter.Opening area in the Linear area-opening relationship parameterization

This parameter is active when the Opening area parameterization block parameter is set to Linear area-pressure relationship.

Opening area of a valve in the fully closed position, when only internal leakage between its respective ports remains. The leakage area is the same in the pressure-reducing and pressure-relief valves. This parameter serves primarily to ensure that closure of the valve does not cause portions of the hydraulic network to become isolated. The exact value specified here is less important than its being a small number greater than zero.

Method by which to calculate the opening area of the valve. The default setting prescribes a linear relationship between the opening area of the valve and the pressure drop between the outlet and the vent opening. The alternative setting allows for a general, nonlinear relationship to be specified in tabulated form.

Vector of pressure drops from port P to port A at which to specify the opening area of the valve. The vector elements must increase monotonically from left to right. This order is important when specifying the Opening area vector for reducing valve block parameter.

shut-offvalvetypes

There are two types of water shut-off valves for typical city dwellings: the outside water shut-off valve controlled by the city and the one that you can control inside the house. The city’s valve is always located on the streetside of your water meter, often near the edge of your yard. Since it is not advisable to tamper with the city’s valve, we’ll only focus on locating your indoor valve.

This parameter is active when the Opening area parameterization block parameter is set to Linear area-pressure relationship.

The Pressure Reducing 3-Way Valve block models the flow through a valve that constricts and, if necessary, vents (via a separate line) so as to maintain a preset pressure differential between its outlet (port A) and its surroundings (T, the vent). The valve combines the functions of two more elementary valves, one a pressure-reducing valve, the other a pressure-relief valve.

The Hydraulics (Isothermal) library will be removed in a future release. Use the Isothermal Liquid library instead. (since R2020a)

Reynolds number at which the flow is assumed to transition between laminar and turbulent regimes.

The calculation of the critical pressure depends on the setting of the Laminar transition specification block parameter. If this parameter is in the default setting of By pressure ratio:

If the Valve parameterization block parameter is set to Tabulated data - Area vs. pressure, the valve opening areas are computed as:

SLeak is the value specified in the Leakage area block parameter.

This parameter is active when the Opening area parameterization block parameter is set to Linear area-pressure relationship.

pCrit is the pressure differential at which the flow shifts between the laminar and turbulent flow regimes.

If you still can’t find the main water shut-off valve, it should be listed on your property inspection report from when you purchased the house. Also, builders often place the valves in or around main, ground-level bathrooms, which could mean that it’s not necessarily on an outside wall but could be in a closet near the bathroom.

Measure of the time taken by the valve to transition from its current opening area to a new steady-state value. The block uses this parameter to calculate the rate at which a valve is opening and from it the instantaneous opening area at the next time step.

The pressure-reducing valve runs between the inlet (P) and the outlet (A). It is normally open but closes as needed to combat pressure fluctuations upstream of the outlet. The pressure-relief valve runs between the outlet (A) and the vent (T). It is normally closed but opens if the outlet pressure should exceed (by a specified transition amount) the pressure regulation range of the pressure-reducing valve.

Libraries: Simscape / Fluids / Hydraulics (Isothermal) / Valves / Pressure Control Valves

Locating water shut-off valves indoors can be a bit tricky. Hopefully, locating yours is simple, and you can easily find the knob or lever on a border wall. However, if it’s not so easy to locate, you’ll need to play “plumbing detective.” (Note that it won’t be under a sink or next to the water heater.) Your valve is likely in one of these places:

Choice of whether to capture the opening dynamics of the valve. Selecting Include valve opening dynamics causes the valve to open gradually, so as to approach its new steady-state area over a small time span. The characteristic time for such transitions is given in the Opening time constant block parameter.

where the tanh term serves to smooth the transitions to the fully open and fully closed valve positions. In the equation:

Sure, “Where is the water shut-off valve?” may not be the first question you ask when you purchase a new home. However, it could prove to be one of the most important questions, considering how much money—and how many headaches—the knowledge could end up saving you if your pipes are leaking.

In addition to understanding how to turn off the water to your house in an emergency, you can also learn more about fixing common toilet problems or what to do if you're dealing with frozen pipes.