diff --git a/BaseMQ.cpp b/BaseMQ.cpp
index c1a5ad5..ee09891 100644
--- a/BaseMQ.cpp
+++ b/BaseMQ.cpp
@@ -1,14 +1,14 @@
 #include "BaseMQ.h"
 
-BaseMQ::BaseMQ(uint8_t pin) {
-  _pin = pin;
+BaseMQ::BaseMQ(uint8_t pin) :
+  _pin (pin) {
 }
 
-BaseMQ::BaseMQ(uint8_t pin, uint8_t pinHeater) {
-  _pin = pin;
-  _pinHeater = pinHeater;
+BaseMQ::BaseMQ(uint8_t pin, uint8_t pinHeater) : 
+  _pin (pin),
+  _pinHeater (pinHeater)
+{
   pinMode(_pinHeater, OUTPUT);
-  _prMillis = 0;
 }
 
 // калибровка датчика
@@ -26,8 +26,7 @@ void BaseMQ::calibrate() {
   }
   ro = ro/MQ_SAMPLE_TIMES;
   ro = ro/getRoInCleanAir();
-  _ro = ro;
-  _stateCalibrate = true;
+  calibrate (ro);
 }
 
 void BaseMQ::heaterPwrHigh() {
@@ -49,14 +48,14 @@ void BaseMQ::heaterPwrOff() {
 }
 
 // сопротивление датчика
-float BaseMQ::calculateResistance(int rawAdc) {
+float BaseMQ::calculateResistance(int rawAdc) const {
   float vrl = rawAdc*(5.0 / 1023);
   float rsAir = (5.0 - vrl)/vrl*getRL();
   return rsAir;
 }
 
 // считывание датчика
-float BaseMQ::readRs() {
+float BaseMQ::readRs() const {
   float rs = 0;
   for (int i = 0; i < MQ_SAMPLE_TIMES; i++) {
     rs += calculateResistance(analogRead(_pin));
@@ -66,26 +65,23 @@ float BaseMQ::readRs() {
   return rs;
 }
 
-float BaseMQ::getRo() {
-  return _ro;
+unsigned long BaseMQ::readScaled(float a, float b) const {
+  float ratio = readRatio();
+  return exp((log(ratio)-b)/a);
 }
 
-bool BaseMQ::isCalibrated() {
-  return _stateCalibrate;
+float BaseMQ::readRatio() const {
+  return readRs()/getRo();
 }
 
-float BaseMQ::readRatio() {
-  return readRs()/_ro;
-}
-
-bool BaseMQ::heatingCompleted() {
+bool BaseMQ::heatingCompleted() const {
   if ((_heater) && (!_cooler) && (millis() - _prMillis > 60000))
     return true;
   else
     return false;
 }
 
-bool BaseMQ::coolanceCompleted() {
+bool BaseMQ::coolanceCompleted() const {
   if ((_heater) && (_cooler) && (millis() - _prMillis > 90000))
     return true;
   else
diff --git a/BaseMQ.h b/BaseMQ.h
index 6aaf1bc..d80cab1 100644
--- a/BaseMQ.h
+++ b/BaseMQ.h
@@ -16,24 +16,32 @@ public:
 	void heaterPwrLow();
 	void heaterPwrOff();
 	void cycleHeat();
-	bool heatingCompleted();
-	bool coolanceCompleted();
-	bool isCalibrated();
 	bool atHeatCycleEnd();
-	float getRo();
-	float readRatio();
+	bool heatingCompleted() const;
+	bool coolanceCompleted() const;
+	float readRatio() const;
+	inline bool isCalibrated() const {
+		return _stateCalibrate;
+	};
+	inline float getRo() const {
+		return _ro;
+        };
+
 protected:
+	unsigned long readScaled(float a, float b) const;
+	virtual float getRoInCleanAir() const = 0;
+	virtual int getRL() const = 0;
+
+private:
 	bool _heater = false;
 	bool _cooler = false;
 	bool _stateCalibrate = false;
-	unsigned long _prMillis;
-	float _ro;
+	unsigned long _prMillis = 0;
+	float _ro = 1.0f;
 	uint8_t _pin;
 	uint8_t _pinHeater;
-	float readRs();
-	float calculateResistance(int rawAdc);
-	virtual float getRoInCleanAir() const = 0;
-	virtual int getRL() const = 0;
+	float readRs() const;
+	float calculateResistance(int rawAdc) const;
 };
 
-#endif 
\ No newline at end of file
+#endif 
diff --git a/MQ2.cpp b/MQ2.cpp
index 6c0a29d..0b897de 100644
--- a/MQ2.cpp
+++ b/MQ2.cpp
@@ -9,22 +9,17 @@ MQ2::MQ2(uint8_t pin, uint8_t pinHeater)
 }
 
 unsigned long MQ2::readLPG() {
-  return readPpm(-0.45, 2.95);
+  return readScaled(-0.45, 2.95);
 }
 
 unsigned long MQ2::readMethane() {
-  return readPpm(-0.38, 3.21);
+  return readScaled(-0.38, 3.21);
 }
 
 unsigned long MQ2::readSmoke() {
-  return readPpm(-0.42, 3.54);
+  return readScaled(-0.42, 3.54);
 }
 
 unsigned long MQ2::readHydrogen() {
-  return readPpm(-0.48, 3.32);
-}
-
-int MQ2::readPpm(float a, float b) {
-  float ratio = readRs()/_ro;
-  return pow(M_E, (log(ratio)-b)/a);
+  return readScaled(-0.48, 3.32);
 }
diff --git a/MQ2.h b/MQ2.h
index a563c10..6f1e2bb 100644
--- a/MQ2.h
+++ b/MQ2.h
@@ -12,11 +12,10 @@ public:
 	unsigned long readSmoke();
 	unsigned long readHydrogen();
 private:
-	int readPpm(float a, float b);
 	// Резистор установленный на плату (кОм)
 	virtual int getRL() const { return 5; }
 	// коефициент чистого воздуха
 	virtual float getRoInCleanAir() const { return 9.83; }
 };
 
-#endif  // MQ2_H_
\ No newline at end of file
+#endif  // MQ2_H_
diff --git a/MQ3.cpp b/MQ3.cpp
index 2d4e321..71053b0 100644
--- a/MQ3.cpp
+++ b/MQ3.cpp
@@ -9,14 +9,9 @@ MQ3::MQ3(uint8_t pin, uint8_t pinHeater)
 }
 
 float MQ3::readAlcoholMgL() {
-  return readMgL(-0.66, -0.62);
+  return readScaled(-0.66, -0.62);
 }
 
 float MQ3::readAlcoholPpm() {
-  return readMgL(-0.66, -0.62)*2.2;
-}
-
-float MQ3::readMgL(float a, float b) {
-  float ratio = readRs()/_ro;
-  return pow(M_E, (log(ratio)-b)/a);
+  return readScaled(-0.66, -0.62)*2.2;
 }
diff --git a/MQ3.h b/MQ3.h
index e796480..7bfc1fc 100644
--- a/MQ3.h
+++ b/MQ3.h
@@ -10,11 +10,10 @@ public:
 	float readAlcoholMgL();
 	float readAlcoholPpm();
 private:
-	float readMgL(float a, float b);
 	// Резистор установленный на плату (кОм)
 	virtual int getRL() const { return 200; }
 	// коефициент чистого воздуха
 	virtual float getRoInCleanAir() const { return 60; }
 };
 
-#endif  // MQ3_H_
\ No newline at end of file
+#endif  // MQ3_H_
diff --git a/MQ4.cpp b/MQ4.cpp
index f377862..c63496e 100644
--- a/MQ4.cpp
+++ b/MQ4.cpp
@@ -9,10 +9,5 @@ MQ4::MQ4(uint8_t pin, uint8_t pinHeater)
 }
 
 unsigned long MQ4::readMethane() {
-  return readPpm(-0.36, 2.54);
-}
-
-int MQ4::readPpm(float a, float b) {
-  float ratio = readRs()/_ro;
-  return pow(M_E, (log(ratio)-b)/a);
+  return readScaled(-0.36, 2.54);
 }
diff --git a/MQ4.h b/MQ4.h
index a8b1f38..1555fd2 100644
--- a/MQ4.h
+++ b/MQ4.h
@@ -9,11 +9,10 @@ public:
 	MQ4(uint8_t pin, uint8_t pinHeater);
 	unsigned long readMethane();
 private:
-	int readPpm(float a, float b);
 	// Резистор установленный на плату (кОм)
 	virtual int getRL() const { return 20; }
 	// коефициент чистого воздуха
 	virtual float getRoInCleanAir() const { return 4.4; }
 };
 
-#endif  // MQ4_H_
\ No newline at end of file
+#endif  // MQ4_H_
diff --git a/MQ5.cpp b/MQ5.cpp
index a462094..2ab0b1e 100644
--- a/MQ5.cpp
+++ b/MQ5.cpp
@@ -9,14 +9,9 @@ MQ5::MQ5(uint8_t pin, uint8_t pinHeater)
 }
 
 unsigned long MQ5::readLPG() {
-  return readPpm(-0.39, 1.73);
+  return readScaled(-0.39, 1.73);
 }
 
 unsigned long MQ5::readMethane() {
-  return readPpm(-0.38, 1.97);
-}
-
-int MQ5::readPpm(float a, float b) {
-  float ratio = readRs()/_ro;
-  return pow(M_E, (log(ratio)-b)/a);
+  return readScaled(-0.38, 1.97);
 }
diff --git a/MQ5.h b/MQ5.h
index a2e3eda..30accb8 100644
--- a/MQ5.h
+++ b/MQ5.h
@@ -10,11 +10,10 @@ public:
 	unsigned long readLPG();
 	unsigned long readMethane();
 private:
-	int readPpm(float a, float b);
 	// Резистор установленный на плату (кОм)
 	virtual int getRL() const { return 20; }
 	// коефициент чистого воздуха
 	virtual float getRoInCleanAir() const { return 6.5; }
 };
 
-#endif  // MQ5_H_
\ No newline at end of file
+#endif  // MQ5_H_
diff --git a/MQ6.cpp b/MQ6.cpp
index 05843fc..d60cb26 100644
--- a/MQ6.cpp
+++ b/MQ6.cpp
@@ -9,10 +9,5 @@ MQ6::MQ6(uint8_t pin, uint8_t pinHeater)
 }
 
 unsigned long MQ6::readLPG() {
-  return readPpm(-0.42, 2.91);
-}
-
-int MQ6::readPpm(float a, float b) {
-  float ratio = readRs()/_ro;
-  return pow(M_E, (log(ratio)-b)/a);
+  return readScaled(-0.42, 2.91);
 }
diff --git a/MQ6.h b/MQ6.h
index c474480..fb14bc6 100644
--- a/MQ6.h
+++ b/MQ6.h
@@ -9,11 +9,10 @@ public:
 	MQ6(uint8_t pin, uint8_t pinHeater);
 	unsigned long readLPG();
 private:
-	int readPpm(float a, float b);
 	// Резистор установленный на плату (кОм)
 	virtual int getRL() const { return 20; }
 	// коефициент чистого воздуха
 	virtual float getRoInCleanAir() const { return 10; }
 };
 
-#endif  // MQ6_H_
\ No newline at end of file
+#endif  // MQ6_H_
diff --git a/MQ7.cpp b/MQ7.cpp
index dcb8563..abbc023 100644
--- a/MQ7.cpp
+++ b/MQ7.cpp
@@ -9,10 +9,5 @@ MQ7::MQ7(uint8_t pin, uint8_t pinHeater)
 }
 
 unsigned long MQ7::readCarbonMonoxide() {
-  return readPpm(-0.77, 3.38);
-}
-
-int MQ7::readPpm(float a, float b) {
-  float ratio = readRs()/_ro;
-  return pow(M_E, (log(ratio)-b)/a);
+  return readScaled(-0.77, 3.38);
 }
diff --git a/MQ7.h b/MQ7.h
index be281eb..cbda104 100644
--- a/MQ7.h
+++ b/MQ7.h
@@ -9,11 +9,10 @@ public:
 	MQ7(uint8_t pin, uint8_t pinHeater);
 	unsigned long readCarbonMonoxide();
 private:
-	int readPpm(float a, float b);
 	// Резистор установленный на плату (кОм)
 	virtual int getRL() const { return 10; }
 	// коефициент чистого воздуха
 	virtual float getRoInCleanAir() const { return 27; }
 };
 
-#endif  // MQ7_H_
\ No newline at end of file
+#endif  // MQ7_H_
diff --git a/MQ8.cpp b/MQ8.cpp
index c2897d1..762e032 100644
--- a/MQ8.cpp
+++ b/MQ8.cpp
@@ -9,10 +9,5 @@ MQ8::MQ8(uint8_t pin, uint8_t pinHeater)
 }
 
 unsigned long MQ8::readHydrogen() {
-  return readPpm(-1.52, 10.49);
-}
-
-int MQ8::readPpm(float a, float b) {
-  float ratio = readRs()/_ro;
-  return pow(M_E, (log(ratio)-b)/a);
+  return readScaled(-1.52, 10.49);
 }
diff --git a/MQ8.h b/MQ8.h
index ceb18ea..fae336c 100644
--- a/MQ8.h
+++ b/MQ8.h
@@ -9,11 +9,10 @@ public:
 	MQ8(uint8_t pin, uint8_t pinHeater);
 	unsigned long readHydrogen();
 private:
-	int readPpm(float a, float b);
 	// Резистор установленный на плату (кОм)
 	virtual int getRL() const { return 10; }
 	// коефициент чистого воздуха
 	virtual float getRoInCleanAir() const { return 70; }
 };
 
-#endif  // MQ8_H_
\ No newline at end of file
+#endif  // MQ8_H_
diff --git a/MQ9.cpp b/MQ9.cpp
index 95dd875..efc80ca 100644
--- a/MQ9.cpp
+++ b/MQ9.cpp
@@ -9,18 +9,13 @@ MQ9::MQ9(uint8_t pin, uint8_t pinHeater)
 }
 
 unsigned long MQ9::readLPG() {
-  return readPpm(-0.48, 3.33);
+  return readScaled(-0.48, 3.33);
 }
 
 unsigned long MQ9::readMethane() {
-  return readPpm(-0.38, 3.21);
+  return readScaled(-0.38, 3.21);
 }
 
 unsigned long MQ9::readCarbonMonoxide() {
-  return readPpm(-0.48, 3.10);
-}
-
-int MQ9::readPpm(float a, float b) {
-  float ratio = readRs()/_ro;
-  return pow(M_E, (log(ratio)-b)/a);
+  return readScaled(-0.48, 3.10);
 }
diff --git a/MQ9.h b/MQ9.h
index 4a4b28f..b375598 100644
--- a/MQ9.h
+++ b/MQ9.h
@@ -11,11 +11,10 @@ public:
 	unsigned long readMethane();
 	unsigned long readCarbonMonoxide();
 private:
-	int readPpm(float a, float b);
 	// Резистор установленный на плату (кОм)
 	virtual int getRL() const { return 10; }
 	// коефициент чистого воздуха
 	virtual float getRoInCleanAir() const { return 9.8; }
 };
 
-#endif  // MQ9_H_
\ No newline at end of file
+#endif  // MQ9_H_