JPH0148966B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrafiltration measuring device that measures the difference between the flow rate of dialysis fluid flowing out from a dialyzer and the flow rate of dialysate flowing into the dialyzer as an ultrafiltration amount.

<Prior art> As shown in Fig. 1, the dialysis machine has a liquid supply line 1.
Dialysate is supplied to the dialyzer 12 through the dialyzer 1 , and the dialysate effluent from the dialyzer 12 is discharged through the drain line 13 . The patient's blood is supplied to the dialyzer 12 through a blood line 14, and the blood from which waste products have been removed by dialysis in the dialyzer 12 is returned to the patient through a blood line 15.

In the conventional ultraviolet amount measuring device, a flowmeter 1 is installed in the liquid supply line 11 and the liquid drainage line 13, respectively.
6 and 17 are provided, the flow rate F _i of the dialysate flowing into the dialyzer 12 is measured by the flow meter 16 to obtain the measured value V _i , and the flow rate F _p of the dialysate waste fluid discharged from the dialyzer 12 is determined.
was measured with a flowmeter 17 to obtain a measured value V _p , and V _p −V _i was determined as an ultraviolet amount.

However, this conventional ultraviolet amount measuring device has the following problems. That is, a flow meter generally has a measurement error, and if the flow rate is F and the flow rate sensor output signal of the flow meter is E, then the formula E=k _F +E ₀ holds true. Here, k is the flow rate-sensor output signal conversion coefficient, and E ₀ is the zero error, that is, the sensor output signal when the flow rate F is zero. Also, if the flowmeter output value is V, then the distance between V and E is V=μ _E +ε
holds true. Here, μ is the sensor output signal-flowmeter output value conversion coefficient, and ε is the zero error, that is, the flowmeter output value output when the sensor output signal is zero. Normally, this flowmeter output value V is used as the final output in most cases, and in the conventional ultra-overflow measuring device shown in FIG. 1, the output value V ₁ of the flowmeter 16 is V ₁ = μ ₁ E ₁ +ε ₁ = μ ₁ (k ₁ F _i +E ₀₁ ) + ε ₁ Also, the output value V ₂ of the flowmeter 17 is V ₂ = μ ₂ E ₂ +ε ₂ = μ ₂ (k ₂ F _p +E ₀₂ )+ε ₂ can be expressed respectively. Therefore, the ultraviolet amount is V ₂ −V ₁ =μ ₂ E ₂ +ε ₂ −(μ ₁ E ₁ +ε ₁ ) = μ ₂ (k ₂ F _p +E ₀₂ )+ε ₂ −μ ₁ (k ₁ F _i +E ₀₁ )−ε ₁ =(μ ₂ k ₂ F _p −μ ₁ k ₁ F _i ) +(μ ₂ E ₀₂ −μ ₁ E ₀₁ )+(ε ₂ −ε ₁ )……(1). If both flowmeters 16 and 17 have no errors, μ ₂ k ₂ = μ ₁ k ₁ = 1, E ₀₁ = E ₀₂ =
ε ₂ =ε ₁ =0. However, since errors are always included in reality, accurate measurements cannot be made when considering equation (1). If the sensor output signal-flowmeter output value conversion coefficient and flow rate-sensor output signal conversion coefficient in the case of zero error are μ ₀ and k ₀ , respectively, μ ₁ = μ ₀ +Δμ ₁ ,
It can be written as μ ₂ =μ ₀ +Δμ ₂ , k ₁ =k ₀ +Δk ₁ , and k ₂ =k ₀ +Δk ₂ . Using this, equation (1) becomes equation (2).

V ₂ −V ₁ = (μ ₀ +Δμ ₂ ) (k ₀ +Δk ₂ ) F _p − (μ ₀ +Δμ ₁ ) (k ₀ +Δk ₁ ) F _i +C ₀ = μ ₀ k ₀ (F _p −F _i )+μ ₀ (Δk ₂ F _p −Δk ₁ F _i ) +k ₀ (Δμ ₂ F _p −Δμ ₁ F _i )+(Δμ ₂ Δk ₂ F _p −Δμ ₁ Δk ₁ F _i )+C ₀ ...(2) However, C ₀ = μ ₂ E ₀₂ −μ ₁ E ₀₁ +ε ₂ −ε _1Here , μ ₀・k ₀ =1, and the true value of the limit excess is only the first term, and the other terms are errors. be. These errors are Δk ₁ , Δk ₂ , Δμ ₁ , Δμ ₂ , E ₀₁ , E ₀₂ , ε ₁ ,
It is determined by the value of ε ₂ , which varies depending on the flowmeter. For example, the flow rate flowing into the dialyzer 12 (hereinafter referred to as the inlet side flow rate) is 500 ml/min, the error of the flow meter 16 is +1%, and the flow rate flowing out from the dialyzer 12 (hereinafter referred to as the outlet side flow rate) is 505 ml/min. , flow meter 1
Assuming that the error of flowmeter 7 is -1% (the error of normal flowmeters is often ±1% or more), the output value of flowmeter 16 will be 505ml/min, and the output value of flowmeter 17 will be 505ml/min.
The output value is 449.95ml/min. Therefore, while the actual ultraviolet amount is 5 ml/min, the measured value is -5.05 ml/min, which is a completely unbelievable value. Ultra-overdose measurements are typically ±10 of the true value.
There is no practical problem if the error range is about %, but if the inlet flow rate is 500 ml/min and the outlet flow rate is 505 ml/min, in order for the measurement error of the limit excess to be within ±10%, (505- 500)×±0.1/2=±0.25ml/
A flowmeter with a resolution of min or higher is required.
This means that when measuring a flow rate of about 500 ml/min, the error is less than ±0.25/500, that is, less than ±0.05%, which is a high degree of accuracy, and such a highly accurate flow meter is unrealistic.

In other words, in the conventional technology in which two flowmeters 16 and 17 are used and the difference between their output values is measured as an ultra-limit amount, the above-mentioned Δk ₁ , Δk ₂ , Δμ ₁ , Δμ ₂ , E ₀₁ ,
Errors due to E ₀₂ , ε ₁ , and ε ₂ always occur, making it impossible to accurately measure the ultraviolet amount.

<Summary of the Invention> The object of the present invention is to provide an apparatus for measuring the ultraviolet amount from the difference between the flow rate of the outflow dialysis fluid and the flow rate of the inflow dialysate, without using a particularly high-precision flowmeter. The idea is to make it possible to measure excess amounts.

According to this invention, the mode switching means can switch between a measurement mode in which dialysis is performed using a dialyzer and an ultra-excess amount is measured, and a calibration mode in which the characteristics of a flowmeter are calibrated to measure outflow dialysis effluent. It is configured as follows. When switched to the calibration mode, the same flow rate of liquid is allowed to flow through the flowmeter that measures inflow dialysate and the flowmeter that measures outflow dialysate, and each flowmeter at that time Using the sensor output signal of and the characteristic value of the flowmeter that measures the inflow dialysate, the characteristics of the flowmeter that measures the outflow dialysis fluid are calibrated based on the characteristics of the flowmeter that measures the inflow dialysate. Ru.

<Example> FIG. 2 shows an example of the ultraviolet amount measuring device according to the present invention, and parts corresponding to those in FIG. 1 are given the same reference numerals. In this invention, the control section 21
It is possible to switch between a measurement mode for measuring the ultra-limit excess amount and a calibration mode for calibrating the flowmeter 17 by controlling the flowmeter 17. In its calibration mode, flow meters 16 and 17 are allowed to flow the same flow rate of liquid simultaneously. Therefore, in this embodiment, a switching valve 22 is provided in the liquid supply line 11 between the flow meter 16 and the dialyzer 12, and a switching valve 23 is provided in the drain line 13 between the dialyzer 12 and the flow meter 17.
are respectively inserted, and a side passage 24 is connected between the switching valves 22 and 23.

In the measurement mode, the dialysate in the liquid supply line 11 flows between the flow rate sensor 16a of the flow meter 16 and the switching valve 2.
The liquid flows through the ports a and b of No. 2, the dialyzer 12, the ports b and a of the switching valve 23, and the flow rate sensor 17a of the flow meter 17, and is discharged from the drain line 13. On the other hand, in the calibration mode, the dialysate flows from the flow rate sensor 16a to the ports a and c of the switching valve 22 to the side passage 24 to the switching valve 23.
Flowed through port ca-flow sensor 17a.

The flow rate sensor 16a has already been calibrated, and the coefficients k 1 and E ₀₁ indicating its characteristics are known. However, if the coefficients k ₁ and E 01 are not yet calibrated, the coefficients k 1 and E 01 are known. Linear regression is performed based on the obtained data, and the regression formula is used as the conversion formula,
Thereby, the obtained coefficients k ₁ and E ₀₁ may be used. Assuming that the output signal of the flow rate sensor 16a is E ₁ and the flow rate is F, E ₁ =k ₁ F+E ₀₁ (3) from the above. Furthermore, since the output signal of the flow rate sensor 16a is normally a minute signal, it is necessary to convert this output signal E ₁ into a flow meter output value V ₁ corresponding to the flow rate. ₁ and use the equation solved for V ₁ . This conversion is performed by the signal processing circuit 16b of the flowmeter 16;
Since an inherent error occurs in the conversion at b, the following relationship generally holds: V ₁ =μ ₁ E ₁ +ε ₁ (4).

On the other hand, the flow rate sensor 17a also has a unique flow rate-sensor output signal conversion formula, although this is unknown, and this can be expressed as E ₂ =k ₂ F+E ₀₂ (5). Since the coefficients k ₂ and E ₀₂ are sensor-specific, it is impossible to correct them. However, as in the flowmeter 16, the output signal E ₂ of the flow rate sensor 17a is processed by the signal processing circuit 17b.
The formula for converting the value into the flowmeter output value V ₂ is expressed as V ₂ =μ ₂ E ₂ +ε ₂ (6), but the conversion coefficients μ ₂ and ε ₂ at this time can be corrected.

Therefore, in the calibration mode, the characteristics of the flowmeter 17 are calibrated in the following manner using the characteristics of the flowmeter 16 as a reference.

The flow rate in calibration mode is F _c , the output signals of flow sensors 16a and 17a are E _c1 and E _c2 , respectively, and the output values of flow meters 16 and 17 are V _c1 and V _c2 , respectively.
The output value conversion coefficient for μ of the flowmeter 17 is μ _c2
Then, in the calibration mode, since the same flow rate F _c flows, V _c2 = V _c1 , that is, from equations (4) and (6), μ _c2 E _c2 +
It must be ε ₂ = μ ₁ E _c1 + ε ₁ . Therefore, μ _c2
Setting E _c2 = μ ₁ E _c1 and ε ₂ = ε ₁ , the calculation unit 25 directly takes in E _c1 and E _c2 under the control of the control unit 21, and calculates the values and the known output for the flowmeter 16. Using the value conversion coefficients μ ₁ and ε ₁ , the output value conversion coefficients μ _c2 and ε ₂ of the flow meter 17 are determined as follows.

μ _c2 = μ ₁ E _c1 /E _c2 ...(7) ε ₂ = ε ₁ ...(8) Then, the flowmeter output value is calculated from the sensor output signals E ₁ and E ₂ in the signal processing circuits 16b and 17b in the measurement mode. The conversion formula to V ₁ and V ₂ is V ₁ = μ ₁ E ₁ + ε ₁ ...(4), V ₂ = μ _c2 E ₂ + ε ₁ = (μ ₁ E _c1 /E _c2 ) E ₂ + ε ₁ ……(9) Calibrate. For example, E _c =500ml/min, k ₁ =
0.0105, E ₀₁ = 0.12, μ ₁ = 95, ε ₁ = −5.15, E _c2 =
Taking the case of 5.02 as an example, from equations (3), (7), and (8), μ _c2 = 95 × (0.0105 × 500 + 0.12) / 5.02 = 101.6235 ε ₂ = −5.15, and signal processing in measurement mode The conversion formula from the sensor output signal to the flowmeter output value in circuits 16b and 17b is calibrated as V ₁ =95×E ₁ −5.15 and V ₂ =101.6235×E ₂ −5.15.

As described above, in the calibration mode, the characteristics μ ₂ , E _c1 , ε ₁ of the flow meter 17 are used as the reference _,
ε ₂ is calibrated. After this, the measurement mode is entered, and the measurement error in the measurement mode will be described below.

The flow rate of dialysate flowing through the flow rate sensor 16a in the measurement mode is F _i , the flow rate of dialysis effluent flowing through the flow rate sensor 17a is F _p , and the output voltages of the flow rate sensors 16 a and 17a at that time are F _i , F _p and flow rate, respectively. Letting the measured output values be V _i and V _p , respectively, E _i =k ₁ F _i +E ₀₁ and E _p =k ₂ F _p +E ₀₂ from equations (3) and (5), and in the signal processing circuits 16b and 17b. The conversion formula to the flowmeter output value is as follows from equations (4) and (9), respectively: V _i =μ ₁ E _i +ε ₁ ...(10) V _p =μ _c2 E _p +ε ₁ ...(11). Therefore, the measured value U _pb of the ultraviolet excess is as follows.

U _pb = V _p − V _i = μ _c2 (k ₂ F _p E ₀₂ ) − μ ₁ (k ₁ F _i E ₀₁ ) = μ _c2 k ₂ F _p − μ ₁ k ₁ F _i + (μ _c2 E ₀₂ −μ ₁ E ₀₁ ) ...(12) As mentioned in the previous calibration mode, μ _c2 E _c2 = μ ₁ E _c1
Therefore, from equations (3) and (5), μ _c2 (k ₂ F _c E ₀₂ ) = μ ₁ (k ₁ F _c E ₀₁ ), so μ _c2 E ₀₂ −μ ₁ E ₀₁ = −(μ _c2 k ₂ F _c − μ ₁ k ₁ F _c ), and by substituting this equation into equation (12), the measured value U _pb of the ultraviolet excess amount becomes as follows.

U _pb =μ _c2 k ₂ F _p −μ ₁ k ₁ F _i −(μ _c2 k ₂ F _c −μ ₁ k ₁ F _c )
...(13) Now, if the true value of the ultraviolet amount is U _re , then
U _re is the dialysis fluid flow rate F _i subtracted from the dialysis fluid flow rate F _p , and is calculated as follows.

U _re =F _p −F _i ...(14) Therefore, the measurement error δ of the ultraviolet amount is obtained by subtracting equation (14) from equation (13), δ=U _pb −U _re = μ _c2 k ₂ F _p −μ ₁ k ₁ F _i −(μ _c2 k ₂ F _c −μ ₁ k ₁ F _c )−(F _p −F _i ) =μ _c2 k ₂ (F _p −F _c ) −μ ₁ k ₁ (F _i −F _c )−(F _p −F _i ), and therefore the error rate Δ is as follows.

Δ=δ/U _re = (U _pb − U _re )/U _re = {μ _c2 k ₂ (F _p − F _c ) − μ ₁ k ₁ (F _i − F _c ) − (F _p − F _i ) }/(F _p − _{F i} ) ...(15) Now, considering the inlet flow rate F _i in the measurement mode with respect to the flow rate F _c in the calibration mode, it is difficult to change the dialysate flow rate in actual dialysis. There are almost no Also, even if there is a fluctuation in flow rate,
Considering long dialysis times of several hours or more, it fluctuates around a central value F _i and the average value is F _i . Therefore, there is no problem in practical terms considering that F _i =F _c . Therefore, equation (15) becomes Δ=μ _c2 k ₂ −1 (16).

By the way, from equations (7) and (5), μ _c2 = μ ₁ E _c1 /E _c2 and k ₂ = E _c2 −E ₀₂ /F _c , so by substituting these into equation (16), we get the following.

Δ=μ ₁ E _c1 /E _c2・E _c2 −E ₀₂ /F _c −1 = μ ₁ E _c1・(1−E ₀₂ /E _C2 )/F _c −1 Also, from equation (4), μ ₁ E _c1 = V _c1 −ε ₁ , so the measurement error of the ultraviolet amount is as follows.

Δ=V _c1 /F _c (V _c1 -ε ₁ ) (1-E ₀₂ /E _C2 )/V _c1 -1 = V _c1 /F _c (1-ε ₁ /V _c1 ) (1-E ₀₂ /E _c2 )−1 = (1+α)(1−β)(1−γ)−1 ...(17) Here, 1+α=V _c1 /F _c , β=ε ₁ /V _c1 , γ=
E ₀₂ /E _c2 , α, β, and γ are the errors of the flowmeter 16 when the flow rate at the time of calibration was applied, and the flowmeter 16
and its zero error rate for the output signal of the flow rate sensor 17a.

In other words, the measurement error of the ultra-limit excess amount is due to the flow meter 17
depends only on the zero error rate for that sensor output signal.

Now, to explain the case of the previous example, (3)
From equation (4), V _c1 = 95×(0.0105×500+0.12)−
5.15 = 505, ε ₁ = 5.15, so β = -5.15/505 = - 0.0102, E _c2 = 5.02, and E _c2 is E ₀₂ by actually measuring the output value of the flow rate sensor 17a when the flow rate is set to zero.
= 0.24, so γ = 0.24/5.02 = 0.0478, so even if the error of the calibrated flowmeter 16 is +5%, for example, α
= 0.05, so substitute these values into equation (17) and get Δ=(1+0.05)×(1+0.0102)(1−0.0478)−
1 = 0.01, and the measurement error of the ultraviolet amount is +1%.
It's nothing more than that.

By the way, β and γ in equation (17) are considered to be within ±3% in a normal flowmeter. Therefore,
Even when α=±0.05 using the flowmeter 16 with an error of ±5%, from equation (17), (1-0.05) (1-0.03) (1-0.03) -1≦∆≦(1+0.05) ( 1 + 0.03) (1 + 0.03) -1 That is, -0.11≦∆≦0.11, and even in the worst case, the measurement error remains at ±11%.

This degree of error does not pose a practical problem when measuring a minute flow rate such as an ultraviolet flow rate. As described above, by calibrating the characteristics of the flowmeter 17 using the characteristics of the flowmeter 16 as a reference in the calibration mode, and then switching to the measurement mode, two flowmeters having substantially the same characteristics can be used. This is equivalent to measuring the ultra-limit excess amount using the same method, and errors due to differences in flowmeter characteristics can be greatly suppressed.

In the measurement mode, V _i is the dialysate flow rate and V _p is the dialysate waste flow rate (10) and (11), respectively.
The calculation unit 25 calculates V _p −V _i and displays the result on the display unit 26 as the ultra-limit excess amount.

When the ultraoverload measurement device according to the present invention is built into or placed alongside a dialysis machine and enters the preparation mode as a dialysis machine, the above-mentioned calibration mode is also automatically performed, and then the dialysis mode is entered. In this case, only the measurement mode may be performed, or the calibration mode may be automatically performed periodically during the dialysis mode. Alternatively, if necessary, the calibration mode may be manually set to perform the above-described calibration, and then the measurement mode may be manually switched. When only the measurement mode is performed in the dialysis mode, the dialysis time is usually about several hours, so during the dialysis time of this length, the flow rate sensor 17a gets dirty due to the dialysis effluent, and the conversion coefficient of the sensor decreases. It is highly unlikely that k ₂ and E ₀₂ change. However, if the period between one dialysis and the next dialysis is long, water scale and the like may be attached. Therefore, by providing a calibration mode at the same time as the preparation mode or during periodic inspection, the flow rate sensor 17a is washed with clean dialysate.

FIG. 3 shows an embodiment of the invention using a microcomputer, and parts corresponding to those in FIG. 2 are given the same reference numerals. microcomputer 27
The central processing unit (hereinafter referred to as CPU) 28 performs various processes by decoding and executing programs stored in read-only memory (hereinafter referred to as ROM) 29, and stores the data necessary for the processing,
The data being processed is stored in a readable/writable memory (hereinafter referred to as RAM) 31 as necessary.
The CPU 28 provides a valve control signal to the valve control circuit 33 via the input/output section 32, controls switching of the switching valves 22 and 23 based on the output of the valve control circuit 33, and
Through the input/output unit 32, the flow meter output values V ₁ and V ₂ of the flow meters 16 and 17 and the output signals of the flow sensors 16a and 17a in the calibration mode can be taken in, and further V ₂ −V ₁ is calculated, The result is supplied to the display circuit 26a of the display unit 26, and the result is displayed on the display 26.
Display on b. The flow meter 16 is calibrated in advance, and the conversion formula between its sensor output signal E ₁ and the flow rate F is E ₁ = k ₁ F + E ₀₁ (linear regression is performed between the flow rate at the sample point and the sensor output signal). ) and the sensor output signal E ₁
The conversion formula _{V 1 =} μ ₁ E ₁ + ε ₁ between and the flowmeter output value V 1 is known, and the values of these coefficients k ₁ , E ₀₁ , μ ₁ , and ε ₁ are stored in the ROM 29. .

In this embodiment, when booted, ROM2
According to the program fixed in 9, the switching valve 2
Both ports 2 and 23 are controlled so that ports a and c are connected, and after the dialysate from the supply device (not shown) passes through the flow rate sensor 16a, it is transferred to the side path 24 without passing through the dialyzer 12. through the flow sensor 17
be swept away by a. In other words, it is set to calibration mode. In the calibration mode, the characteristics of the flowmeter 17 are calibrated in the following manner using the characteristics of the flowmeter 16 as a reference.

As in the previous example, assuming that the output signals of the flow rate sensors 16a and 17a in the calibration mode are E _c1 and E _c2 , respectively, and the output value conversion coefficient for μ of the flow meter 17 is μ _c2 , the flowchart of FIG. 4 shows. As shown, in step _S1 , the CPU 28 first outputs E _c1 and E _c2.
In addition, the values of the output value conversion coefficients μ ₁ and ε ₁ of the flowmeter 16 as a reference are taken in. Next, in step _S2 , μ _c2 is calculated from μ _c2 = μ ₁ E _c1 /E _c2 . Then, in step _S3 , the output value conversion coefficients μ ₂ and ε ₂ in the measurement mode of the flowmeter 17 are determined as μ ₂ =μ _c2 ε ₂ =ε, respectively.
₁
The calibration value of is stored in the RAM 31.

After processing this calibration mode, the CPU 28
By the program in the ROM 29, the switching valve 22,
23 to connect ports a and b, respectively, and enter the measurement mode. In measurement mode,
The sensor output signals E _i and E _p of the flow meters 16 and 17 are processed by signal processing circuits 16 b and 17 b, respectively, using the output value conversion coefficients (10) and (11) obtained in the calibration mode, as in the previous embodiment. ) are converted into flowmeter output values V _i and V _p, respectively, and the input/output section 32
The data is taken into the CPU 28 through. From this, V _p -V _i is further calculated, and the result is displayed as the limit excess amount on the display 26b via the display circuit 26a.
will be displayed.

As described above, according to the present invention, the error α of the flowmeter 16 and the zero error rate β with respect to its output value are within ±5% and ±3%, respectively, and the flowmeter 17
The zero error rate γ for the sensor output signal is ±3%
As long as the flowmeters 16 and 17 are of the same type, for example, 16 may be an electromagnetic flowmeter, 1
7 may be of a different type, such as an ultrasonic flow meter.

In addition, the reference flowmeter 16 has, for example, a measurement error α and a zero error rate β for the output value of ±1, respectively.
When using a high-accuracy device within %, even if the allowable range of measurement error for the ultraviolet amount is, for example, ±5%, |α|≦0.01, |β|≦0.01, |Δ|≦0.05,
From equation (17), the allowable range of γ for the flowmeter 17 is -0.029≦γ≦0.031, so a normal flowmeter will suffice. In other words, even if you do not use a particularly high-precision flowmeter 17,
It is possible to measure the ultraviolet amount with an error of ±5%. The accuracy of the flowmeter 16 can be improved by linearizing means using a microcomputer or the like, so by doing so, the permissible error range of the flowmeter 17 can be further widened.

Note that the switching valves 22, 23 and the side passage 24 are omitted,
The same flow rate of dialysate may be passed through the dialyzer 12 to the flowmeters 16 and 17 in the calibration mode. In this case, in the calibration mode, the pressure on the blood flow path side of the dialyzer 12 and the pressure on the dialysate flow path are made equal,
Control so that there is no movement of moisture from both sides. Further, in the calibration mode, other liquids may be passed through the flowmeters 16 and 17 instead of the dialysate.

<Effects> As described above, according to the present invention, in the measurement of ultraviolet excess, by providing a calibration mode in addition to the normal measurement mode, errors caused by variations in flowmeters can be minimized, and in particular, high precision Highly accurate measurement is possible without using a flowmeter, and
The flow path of the flow rate sensor 17a exposed to the dialysis fluid can be cleaned with clean dialysis fluid. In addition, regarding the calibration of the flowmeter output value, only the flowmeter 16 for measuring the flow rate on the inlet side is required, and the effort for adjustment can be significantly reduced.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing this conventional ultraviolet amount measuring device, Fig. 2 is a block diagram showing an example of the ultraviolet amount measuring device according to the present invention, and Fig. 3 is a schematic diagram showing an example of the ultraviolet amount measuring device according to the invention. A block diagram showing an example of an ultra-limit excess measuring device, FIG.
3 is a flowchart illustrating an example of the operation of the illustrated apparatus in a calibration mode. 11: Liquid supply line, 12: Dialyzer, 13: Drainage line, 16, 17: Flow meter, 21: Control unit,
22, 23: switching valve, 24: side path, 25: calculation section, 27: microcomputer.

Claims (1)

[Claims] 1. The flow rate of the dialysate flowing into the dialyzer is measured with a first flow meter, the flow rate of the dialysis fluid flowing out from the dialyzer is measured with a second flow meter, and the flow rate of these dialysis fluid and the flow rate of the dialysate are measured. In the ultraviolet measuring device that measures the difference between a mode switching means for switching to a mode switching means, and a mode switching means for causing the same flow rate of liquid to flow through the first flowmeter and the second flowmeter in the calibration mode, and output signals of the respective flowmeters obtained at that time and characteristic values of the first flowmeter. the second flowmeter based on the characteristics of the first flowmeter.
An ultra-overflow measuring device comprising a calibration means for calibrating the characteristics of a flowmeter.